Core and Builtins

• Issue #24305: Prevent import subsystem stack frames from being counted by the warnings.warn(stacklevel=) parameter.
• Issue #24912: Prevent __class__ assignment to immutable built-in objects.
• Issue #24975: Fix AST compilation for PEP 448 syntax.

Library

• Issue #24748: To resolve a compatibility problem found with py2exe and pywin32, imp.load_dynamic() once again ignores previously loaded modules to support Python modules replacing themselves with extension modules. Patch by Petr Viktorin.
• Issue #24635: Fixed a bug in typing.py where isinstance([], typing.Iterable) would return True once, then False on subsequent calls.
• Issue #24989: Fixed buffer overread in BytesIO.readline() if a position is set beyond size. Based on patch by John Leitch.
• Issue #24913: Fix overrun error in deque.index(). Found by John Leitch and Bryce Darling.

Core and Builtins

• Issue #24769: Interpreter now starts properly when dynamic loading is disabled. Patch by Petr Viktorin.
• Issue #21167: NAN operations are now handled correctly when python is compiled with ICC even if -fp-model strict is not specified.
• Issue #24492: A “package” lacking a __name__ attribute when trying to perform a from .. import ... statement will trigger an ImportError instead of an AttributeError.

Library

• Issue #24847: Removes vcruntime140.dll dependency from Tcl/Tk.
• Issue #24839: platform._syscmd_ver raises DeprecationWarning
• Issue #24867: Fix Task.get_stack() for ‘async def’ coroutines

Core and Builtins

• Issue #24667: Resize odict in all cases that the underlying dict resizes.

Library

• Issue #24824: Signatures of codecs.encode() and codecs.decode() now are compatible with pydoc.
• Issue #24634: Importing uuid should not try to load libc on Windows
• Issue #24798: _msvccompiler.py doesn’t properly support manifests
• Issue #4395: Better testing and documentation of binary operators. Patch by Martin Panter.
• Issue #23973: Update typing.py from GitHub repo.
• Issue #23004: mock_open() now reads binary data correctly when the type of read_data is bytes. Initial patch by Aaron Hill.
• Issue #23888: Handle fractional time in cookie expiry. Patch by ssh.
• Issue #23652: Make it possible to compile the select module against the libc headers from the Linux Standard Base, which do not include some EPOLL macros. Patch by Matt Frank.
• Issue #22932: Fix timezones in email.utils.formatdate. Patch from Dmitry Shachnev.
• Issue #23779: imaplib raises TypeError if authenticator tries to abort. Patch from Craig Holmquist.
• Issue #23319: Fix ctypes.BigEndianStructure, swap correctly bytes. Patch written by Matthieu Gautier.
• Issue #23254: Document how to close the TCPServer listening socket. Patch from Martin Panter.
• Issue #19450: Update Windows and OS X installer builds to use SQLite 3.8.11.
• Issue #17527: Add PATCH to wsgiref.validator. Patch from Luca Sbardella.
• Issue #23812: Fix asyncio.Queue.get() to avoid loosing items on cancellation. Patch by Gustavo J. A. M. Carneiro.
• Issue #24791: Fix grammar regression for call syntax: ‘g(*a or b)’.

IDLE

• Issue #23672: Allow Idle to edit and run files with astral chars in name. Patch by Mohd Sanad Zaki Rizvi.
• Issue #24745: Idle editor default font. Switch from Courier to platform-sensitive TkFixedFont. This should not affect current customized font selections. If there is a problem, edit $HOME/.idlerc/config-main.cfg and remove ‘fontxxx’ entries from [Editor Window]. Patch by Mark Roseman.
• Issue #21192: Idle editor. When a file is run, put its name in the restart bar. Do not print false prompts. Original patch by Adnan Umer.
• Issue #13884: Idle menus. Remove tearoff lines. Patch by Roger Serwy.

Documentation

• Issue #24129: Clarify the reference documentation for name resolution. This includes removing the assumption that readers will be familiar with the name resolution scheme Python used prior to the introduction of lexical scoping for function namespaces. Patch by Ivan Levkivskyi.
• Issue #20769: Improve reload() docs. Patch by Dorian Pula.
• Issue #23589: Remove duplicate sentence from the FAQ. Patch by Yongzhi Pan.
• Issue #24729: Correct IO tutorial to match implementation regarding encoding parameter to open function.

Tests

• Issue #24751: When running regrtest with the -w command line option, a test run is no longer marked as a failure if all tests succeed when re-run.

Core and Builtins

• Issue #23573: Restored optimization of bytes.rfind() and bytearray.rfind() for single-byte argument on Linux.
• Issue #24569: Make PEP 448 dictionary evaluation more consistent.
• Issue #24583: Fix crash when set is mutated while being updated.
• Issue #24407: Fix crash when dict is mutated while being updated.
• Issue #24619: New approach for tokenizing async/await. As a consequence, is is now possible to have one-line ‘async def foo(): await ..’ functions.
• Issue #24687: Plug refleak on SyntaxError in function parameters annotations.
• Issue #15944: memoryview: Allow arbitrary formats when casting to bytes. Patch by Martin Panter.

Library

• Issue #23441: rcompleter now prints a tab character instead of displaying possible completions for an empty word. Initial patch by Martin Sekera.
• Issue #24683: Fixed crashes in _json functions called with arguments of inappropriate type.
• Issue #21697: shutil.copytree() now correctly handles symbolic links that point to directories. Patch by Eduardo Seabra and Thomas Kluyver.
• Issue #14373: Fixed segmentation fault when gc.collect() is called during constructing lru_cache (C implementation).
• Issue #24695: Fix a regression in traceback.print_exception(). If exc_traceback is None we shouldn’t print a traceback header like described in the documentation.
• Issue #24620: Random.setstate() now validates the value of state last element.
• Issue #22485: Fixed an issue that caused inspect.getsource to return incorrect results on nested functions.
• Issue #22153: Improve unittest docs. Patch from Martin Panter and evilzero.
• Issue #24580: Symbolic group references to open group in re patterns now are explicitly forbidden as well as numeric group references.
• Issue #24206: Fixed __eq__ and __ne__ methods of inspect classes.
• Issue #24631: Fixed regression in the timeit module with multiline setup.
• Issue #18622: unittest.mock.mock_open().reset_mock would recurse infinitely. Patch from Nicola Palumbo and Laurent De Buyst.
• Issue #23661: unittest.mock side_effects can now be exceptions again. This was a regression vs Python 3.4. Patch from Ignacio Rossi
• Issue #24608: chunk.Chunk.read() now always returns bytes, not str.
• Issue #18684: Fixed reading out of the buffer in the re module.
• Issue #24259: tarfile now raises a ReadError if an archive is truncated inside a data segment.
• Issue #15014: SMTP.auth() and SMTP.login() now support RFC 4954’s optional initial-response argument to the SMTP AUTH command.
• Issue #24669: Fix inspect.getsource() for ‘async def’ functions. Patch by Kai Groner.
• Issue #24688: ast.get_docstring() for ‘async def’ functions.

Build

• Issue #24603: Update Windows builds and OS X 10.5 installer to use OpenSSL 1.0.2d.

Core and Builtins

• Issue #24467: Fixed possible buffer over-read in bytearray. The bytearray object now always allocates place for trailing null byte and it’s buffer now is always null-terminated.
• Upgrade to Unicode 8.0.0.
• Issue #24345: Add Py_tp_finalize slot for the stable ABI.
• Issue #24400: Introduce a distinct type for PEP 492 coroutines; add types.CoroutineType, inspect.getcoroutinestate, inspect.getcoroutinelocals; coroutines no longer use CO_GENERATOR flag; sys.set_coroutine_wrapper works only for ‘async def’ coroutines; inspect.iscoroutine no longer uses collections.abc.Coroutine, it’s intended to test for pure ‘async def’ coroutines only; add new opcode: GET_YIELD_FROM_ITER; fix generators wrapper used in types.coroutine to be instance of collections.abc.Generator; collections.abc.Awaitable and collections.abc.Coroutine can no longer be used to detect generator-based coroutines–use inspect.isawaitable instead.
• Issue #24450: Add gi_yieldfrom to generators and cr_await to coroutines. Contributed by Benno Leslie and Yury Selivanov.
• Issue #19235: Add new RecursionError exception. Patch by Georg Brandl.

Library

• Issue #21750: mock_open.read_data can now be read from each instance, as it could in Python 3.3.
• Issue #24552: Fix use after free in an error case of the _pickle module.
• Issue #24514: tarfile now tolerates number fields consisting of only whitespace.
• Issue #19176: Fixed doctype() related bugs in C implementation of ElementTree. A deprecation warning no longer issued by XMLParser subclass with default doctype() method. Direct call of doctype() now issues a warning. Parser’s doctype() now is not called if target’s doctype() is called. Based on patch by Martin Panter.
• Issue #20387: Restore semantic round-trip correctness in tokenize/untokenize for tab-indented blocks.
• Issue #24456: Fixed possible buffer over-read in adpcm2lin() and lin2adpcm() functions of the audioop module.
• Issue #24336: The contextmanager decorator now works with functions with keyword arguments called “func” and “self”. Patch by Martin Panter.
• Issue #24522: Fix possible integer overflow in json accelerator module.
• Issue #24489: ensure a previously set C errno doesn’t disturb cmath.polar().
• Issue #24408: Fixed AttributeError in measure() and metrics() methods of tkinter.Font.
• Issue #14373: C implementation of functools.lru_cache() now can be used with methods.
• Issue #8232: webbrowser support incomplete on Windows. Patch by Brandon Milam
• Issue #24347: Set KeyError if PyDict_GetItemWithError returns NULL.
• Issue #24348: Drop superfluous incref/decref.
• Issue #24359: Check for changed OrderedDict size during iteration.
• Issue #24368: Support keyword arguments in OrderedDict methods.
• Issue #24362: Simplify the C OrderedDict fast nodes resize logic.
• Issue #24377: Fix a ref leak in OrderedDict.__repr__.
• Issue #24369: Defend against key-changes during iteration.

Tests

• Issue #24373: _testmultiphase and xxlimited now use tp_traverse and tp_finalize to avoid reference leaks encountered when combining tp_dealloc with PyType_FromSpec (see issue #16690 for details)

Documentation

• Issue #24458: Update documentation to cover multi-phase initialization for extension modules (PEP 489). Patch by Petr Viktorin.
• Issue #24351: Clarify what is meant by “identifier” in the context of string.Template instances.

Build

• Issue #24432: Update Windows builds and OS X 10.5 installer to use OpenSSL 1.0.2c.

Core and Builtins

• Issue #24284: The startswith and endswith methods of the str class no longer return True when finding the empty string and the indexes are completely out of range.
• Issue #24115: Update uses of PyObject_IsTrue(), PyObject_Not(), PyObject_IsInstance(), PyObject_RichCompareBool() and _PyDict_Contains() to check for and handle errors correctly.
• Issue #24328: Fix importing one character extension modules.
• Issue #11205: In dictionary displays, evaluate the key before the value.
• Issue #24285: Fixed regression that prevented importing extension modules from inside packages. Patch by Petr Viktorin.

Library

• Issue #23247: Fix a crash in the StreamWriter.reset() of CJK codecs.
• Issue #24270: Add math.isclose() and cmath.isclose() functions as per PEP 485. Contributed by Chris Barker and Tal Einat.
• Issue #5633: Fixed timeit when the statement is a string and the setup is not.
• Issue #24326: Fixed audioop.ratecv() with non-default weightB argument. Original patch by David Moore.
• Issue #16991: Add a C implementation of OrderedDict.
• Issue #23934: Fix inspect.signature to fail correctly for builtin types lacking signature information. Initial patch by James Powell.

Core and Builtins

• Issue #24276: Fixed optimization of property descriptor getter.
• Issue #24268: PEP 489: Multi-phase extension module initialization. Patch by Petr Viktorin.
• Issue #23955: Add pyvenv.cfg option to suppress registry/environment lookup for generating sys.path on Windows.
• Issue #24257: Fixed system error in the comparison of faked types.SimpleNamespace.
• Issue #22939: Fixed integer overflow in iterator object. Patch by Clement Rouault.
• Issue #23985: Fix a possible buffer overrun when deleting a slice from the front of a bytearray and then appending some other bytes data.
• Issue #24102: Fixed exception type checking in standard error handlers.
• Issue #15027: The UTF-32 encoder is now 3x to 7x faster.
• Issue #23290: Optimize set_merge() for cases where the target is empty. (Contributed by Serhiy Storchaka.)
• Issue #2292: PEP 448: Additional Unpacking Generalizations.
• Issue #24096: Make warnings.warn_explicit more robust against mutation of the warnings.filters list.
• Issue #23996: Avoid a crash when a delegated generator raises an unnormalized StopIteration exception. Patch by Stefan Behnel.
• Issue #23910: Optimize property() getter calls. Patch by Joe Jevnik.
• Issue #23911: Move path-based importlib bootstrap code to a separate frozen module.
• Issue #24192: Fix namespace package imports.
• Issue #24022: Fix tokenizer crash when processing undecodable source code.
• Issue #9951: Added a hex() method to bytes, bytearray, and memoryview.
• Issue #22906: PEP 479: Change StopIteration handling inside generators.
• Issue #24017: PEP 492: Coroutines with async and await syntax.

Library

• Issue #14373: Added C implementation of functools.lru_cache(). Based on patches by Matt Joiner and Alexey Kachayev.
• Issue #24230: The tempfile module now accepts bytes for prefix, suffix and dir parameters and returns bytes in such situations (matching the os module APIs).
• Issue #22189: collections.UserString now supports __getnewargs__(), __rmod__(), casefold(), format_map(), isprintable(), and maketrans(). Patch by Joe Jevnik.
• Issue #24244: Prevents termination when an invalid format string is encountered on Windows in strftime.
• Issue #23973: PEP 484: Add the typing module.
• Issue #23086: The collections.abc.Sequence() abstract base class added start and stop parameters to the index() mixin. Patch by Devin Jeanpierre.
• Issue #20035: Replaced the tkinter._fix module used for setting up the Tcl/Tk environment on Windows with a private function in the _tkinter module that makes no permanent changes to the environment.
• Issue #24257: Fixed segmentation fault in sqlite3.Row constructor with faked cursor type.
• Issue #15836: assertRaises(), assertRaisesRegex(), assertWarns() and assertWarnsRegex() assertments now check the type of the first argument to prevent possible user error. Based on patch by Daniel Wagner-Hall.
• Issue #9858: Add missing method stubs to _io.RawIOBase. Patch by Laura Rupprecht.
• Issue #22955: attrgetter, itemgetter and methodcaller objects in the operator module now support pickling. Added readable and evaluable repr for these objects. Based on patch by Josh Rosenberg.
• Issue #22107: tempfile.gettempdir() and tempfile.mkdtemp() now try again when a directory with the chosen name already exists on Windows as well as on Unix. tempfile.mkstemp() now fails early if parent directory is not valid (not exists or is a file) on Windows.
• Issue #23780: Improved error message in os.path.join() with single argument.
• Issue #6598: Increased time precision and random number range in email.utils.make_msgid() to strengthen the uniqueness of the message ID.
• Issue #24091: Fixed various crashes in corner cases in C implementation of ElementTree.
• Issue #21931: msilib.FCICreate() now raises TypeError in the case of a bad argument instead of a ValueError with a bogus FCI error number. Patch by Jeffrey Armstrong.
• Issue #13866: quote_via argument added to urllib.parse.urlencode.
• Issue #20098: New mangle_from policy option for email, default True for compat32, but False for all other policies.
• Issue #24211: The email library now supports RFC 6532: it can generate headers using utf-8 instead of encoded words.
• Issue #16314: Added support for the LZMA compression in distutils.
• Issue #21804: poplib now supports RFC 6856 (UTF8).
• Issue #18682: Optimized pprint functions for builtin scalar types.
• Issue #22027: smtplib now supports RFC 6531 (SMTPUTF8).
• Issue #23488: Random generator objects now consume 2x less memory on 64-bit.
• Issue #1322: platform.dist() and platform.linux_distribution() functions are now deprecated. Initial patch by Vajrasky Kok.
• Issue #22486: Added the math.gcd() function. The fractions.gcd() function now is deprecated. Based on patch by Mark Dickinson.
• Issue #24064: Property() docstrings are now writeable. (Patch by Berker Peksag.)
• Issue #22681: Added support for the koi8_t encoding.
• Issue #22682: Added support for the kz1048 encoding.
• Issue #23796: peek and read1 methods of BufferedReader now raise ValueError if they called on a closed object. Patch by John Hergenroeder.
• Issue #21795: smtpd now supports the 8BITMIME extension whenever the new decode_data constructor argument is set to False.
• Issue #24155: optimize heapq.heapify() for better cache performance when heapifying large lists.
• Issue #21800: imaplib now supports RFC 5161 (enable), RFC 6855 (utf8/internationalized email) and automatically encodes non-ASCII usernames and passwords to UTF8.
• Issue #20274: When calling a _sqlite.Connection, it now complains if passed any keyword arguments. Previously it silently ignored them.
• Issue #20274: Remove ignored and erroneous “kwargs” parameters from three METH_VARARGS methods on _sqlite.Connection.
• Issue #24134: assertRaises(), assertRaisesRegex(), assertWarns() and assertWarnsRegex() checks now emits a deprecation warning when callable is None or keyword arguments except msg is passed in the context manager mode.
• Issue #24018: Add a collections.abc.Generator abstract base class. Contributed by Stefan Behnel.
• Issue #23880: Tkinter’s getint() and getdouble() now support Tcl_Obj. Tkinter’s getdouble() now supports any numbers (in particular int).
• Issue #22619: Added negative limit support in the traceback module. Based on patch by Dmitry Kazakov.
• Issue #24094: Fix possible crash in json.encode with poorly behaved dict subclasses.
• Issue #9246: On POSIX, os.getcwd() now supports paths longer than 1025 bytes. Patch written by William Orr.
• Issue #17445: add difflib.diff_bytes() to support comparison of byte strings (fixes a regression from Python 2).
• Issue #23917: Fall back to sequential compilation when ProcessPoolExecutor doesn’t exist. Patch by Claudiu Popa.
• Issue #23008: Fixed resolving attributes with boolean value is False in pydoc.
• Fix asyncio issue 235: LifoQueue and PriorityQueue’s put didn’t increment unfinished tasks (this bug was introduced when JoinableQueue was merged with Queue).
• Issue #23908: os functions now reject paths with embedded null character on Windows instead of silently truncate them.
• Issue #23728: binascii.crc_hqx() could return an integer outside of the range 0-0xffff for empty data.
• Issue #23887: urllib.error.HTTPError now has a proper repr() representation. Patch by Berker Peksag.
• asyncio: New event loop APIs: set_task_factory() and get_task_factory().
• asyncio: async() function is deprecated in favour of ensure_future().
• Issue #24178: asyncio.Lock, Condition, Semaphore, and BoundedSemaphore support new ‘async with’ syntax. Contributed by Yury Selivanov.
• Issue #24179: Support ‘async for’ for asyncio.StreamReader. Contributed by Yury Selivanov.
• Issue #24184: Add AsyncIterator and AsyncIterable ABCs to collections.abc. Contributed by Yury Selivanov.
• Issue #22547: Implement informative __repr__ for inspect.BoundArguments. Contributed by Yury Selivanov.
• Issue #24190: Implement inspect.BoundArgument.apply_defaults() method. Contributed by Yury Selivanov.
• Issue #20691: Add ‘follow_wrapped’ argument to inspect.Signature.from_callable() and inspect.signature(). Contributed by Yury Selivanov.
• Issue #24248: Deprecate inspect.Signature.from_function() and inspect.Signature.from_builtin().
• Issue #23898: Fix inspect.classify_class_attrs() to support attributes with overloaded __eq__ and __bool__. Patch by Mike Bayer.
• Issue #24298: Fix inspect.signature() to correctly unwrap wrappers around bound methods.

IDLE

• Issue #23184: remove unused names and imports in idlelib. Initial patch by Al Sweigart.

Tests

• Issue #21520: test_zipfile no longer fails if the word ‘bad’ appears anywhere in the name of the current directory.
• Issue #9517: Move script_helper into the support package. Patch by Christie Wilson.

Documentation

• Issue #22155: Add File Handlers subsection with createfilehandler to tkinter doc. Remove obsolete example from FAQ. Patch by Martin Panter.
• Issue #24029: Document the name binding behavior for submodule imports.
• Issue #24077: Fix typo in man page for -I command option: -s, not -S

Tools/Demos

• Issue #24000: Improved Argument Clinic’s mapping of converters to legacy “format units”. Updated the documentation to match.
• Issue #24001: Argument Clinic converters now use accept={type} instead of types={‘type’} to specify the types the converter accepts.
• Issue #23330: h2py now supports arbitrary filenames in #include.
• Issue #24031: make patchcheck now supports git checkouts, too.

Core and Builtins

• Issue #22980: Under Linux, GNU/KFreeBSD and the Hurd, C extensions now include the architecture triplet in the extension name, to make it easy to test builds for different ABIs in the same working tree. Under OS X, the extension name now includes PEP 3149-style information.
• Issue #22631: Added Linux-specific socket constant CAN_RAW_FD_FRAMES. Patch courtesy of Joe Jevnik.
• Issue #23731: Implement PEP 488: removal of .pyo files.
• Issue #23726: Don’t enable GC for user subclasses of non-GC types that don’t add any new fields. Patch by Eugene Toder.
• Issue #23309: Avoid a deadlock at shutdown if a daemon thread is aborted while it is holding a lock to a buffered I/O object, and the main thread tries to use the same I/O object (typically stdout or stderr). A fatal error is emitted instead.
• Issue #22977: Fixed formatting Windows error messages on Wine. Patch by Martin Panter.
• Issue #23466: %c, %o, %x, and %X in bytes formatting now raise TypeError on non-integer input.
• Issue #24044: Fix possible null pointer dereference in list.sort in out of memory conditions.
• Issue #21354: PyCFunction_New function is exposed by python DLL again.

Library

• Issue #23840: tokenize.open() now closes the temporary binary file on error to fix a resource warning.
• Issue #16914: new debuglevel 2 in smtplib adds timestamps to debug output.
• Issue #7159: urllib.request now supports sending auth credentials automatically after the first 401. This enhancement is a superset of the enhancement from issue #19494 and supersedes that change.
• Issue #23703: Fix a regression in urljoin() introduced in 901e4e52b20a. Patch by Demian Brecht.
• Issue #4254: Adds _curses.update_lines_cols() Patch by Arnon Yaari
• Issue #19933: Provide default argument for ndigits in round. Patch by Vajrasky Kok.
• Issue #23193: Add a numeric_owner parameter to tarfile.TarFile.extract and tarfile.TarFile.extractall. Patch by Michael Vogt and Eric Smith.
• Issue #23342: Add a subprocess.run() function than returns a CalledProcess instance for a more consistent API than the existing call* functions.
• Issue #21217: inspect.getsourcelines() now tries to compute the start and end lines from the code object, fixing an issue when a lambda function is used as decorator argument. Patch by Thomas Ballinger and Allison Kaptur.
• Issue #24521: Fix possible integer overflows in the pickle module.
• Issue #22931: Allow ‘[‘ and ‘]’ in cookie values.
• The keywords attribute of functools.partial is now always a dictionary.
• Issue #23811: Add missing newline to the PyCompileError error message. Patch by Alex Shkop.
• Issue #21116: Avoid blowing memory when allocating a multiprocessing shared array that’s larger than 50% of the available RAM. Patch by Médéric Boquien.
• Issue #22982: Improve BOM handling when seeking to multiple positions of a writable text file.
• Issue #23464: Removed deprecated asyncio JoinableQueue.
• Issue #23529: Limit the size of decompressed data when reading from GzipFile, BZ2File or LZMAFile. This defeats denial of service attacks using compressed bombs (i.e. compressed payloads which decompress to a huge size). Patch by Martin Panter and Nikolaus Rath.
• Issue #21859: Added Python implementation of io.FileIO.
• Issue #23865: close() methods in multiple modules now are idempotent and more robust at shutdown. If they need to release multiple resources, all are released even if errors occur.
• Issue #23400: Raise same exception on both Python 2 and 3 if sem_open is not available. Patch by Davin Potts.
• Issue #10838: The subprocess now module includes SubprocessError and TimeoutError in its list of exported names for the users wild enough to use from subprocess import *.
• Issue #23411: Added DefragResult, ParseResult, SplitResult, DefragResultBytes, ParseResultBytes, and SplitResultBytes to urllib.parse.__all__. Patch by Martin Panter.
• Issue #23881: urllib.request.ftpwrapper constructor now closes the socket if the FTP connection failed to fix a ResourceWarning.
• Issue #23853: socket.socket.sendall() does no more reset the socket timeout each time data is sent successfuly. The socket timeout is now the maximum total duration to send all data.
• Issue #22721: An order of multiline pprint output of set or dict containing orderable and non-orderable elements no longer depends on iteration order of set or dict.
• Issue #15133: _tkinter.tkapp.getboolean() now supports Tcl_Obj and always returns bool. tkinter.BooleanVar now validates input values (accepted bool, int, str, and Tcl_Obj). tkinter.BooleanVar.get() now always returns bool.
• Issue #10590: xml.sax.parseString() now supports string argument.
• Issue #23338: Fixed formatting ctypes error messages on Cygwin. Patch by Makoto Kato.
• Issue #15582: inspect.getdoc() now follows inheritance chains.
• Issue #2175: SAX parsers now support a character stream of InputSource object.
• Issue #16840: Tkinter now supports 64-bit integers added in Tcl 8.4 and arbitrary precision integers added in Tcl 8.5.
• Issue #23834: Fix socket.sendto(), use the C Py_ssize_t type to store the result of sendto() instead of the C int type.
• Issue #23618: socket.socket.connect() now waits until the connection completes instead of raising InterruptedError if the connection is interrupted by signals, signal handlers don’t raise an exception and the socket is blocking or has a timeout. socket.socket.connect() still raise InterruptedError for non-blocking sockets.
• Issue #21526: Tkinter now supports new boolean type in Tcl 8.5.
• Issue #23836: Fix the faulthandler module to handle reentrant calls to its signal handlers.
• Issue #23838: linecache now clears the cache and returns an empty result on MemoryError.
• Issue #10395: Added os.path.commonpath(). Implemented in posixpath and ntpath. Based on patch by Rafik Draoui.
• Issue #23611: Serializing more “lookupable” objects (such as unbound methods or nested classes) now are supported with pickle protocols < 4.
• Issue #13583: sqlite3.Row now supports slice indexing.
• Issue #18473: Fixed 2to3 and 3to2 compatible pickle mappings. Fixed ambigious reverse mappings. Added many new mappings. Import mapping is no longer applied to modules already mapped with full name mapping.
• Issue #23485: select.select() is now retried automatically with the recomputed timeout when interrupted by a signal, except if the signal handler raises an exception. This change is part of the PEP 475.
• Issue #23752: When built from an existing file descriptor, io.FileIO() now only calls fstat() once. Before fstat() was called twice, which was not necessary.
• Issue #23704: collections.deque() objects now support __add__, __mul__, and __imul__().
• Issue #23171: csv.Writer.writerow() now supports arbitrary iterables.
• Issue #23745: The new email header parser now handles duplicate MIME parameter names without error, similar to how get_param behaves.
• Issue #22117: Fix os.utime(), it now rounds the timestamp towards minus infinity (-inf) instead of rounding towards zero.
• Issue #23310: Fix MagicMock’s initializer to work with __methods__, just like configure_mock(). Patch by Kasia Jachim.

Build

• Issue #23817: FreeBSD now uses “1.0” the the SOVERSION as other operating systems, instead of just “1”.
• Issue #23501: Argument Clinic now generates code into separate files by default.

Tests

• Issue #23799: Added test.support.start_threads() for running and cleaning up multiple threads.
• Issue #22390: test.regrtest now emits a warning if temporary files or directories are left after running a test.

Tools/Demos

• Issue #18128: pygettext now uses standard +NNNN format in the POT-Creation-Date header.
• Issue #23935: Argument Clinic’s understanding of format units accepting bytes, bytearrays, and buffers is now consistent with both the documentation and the implementation.
• Issue #23944: Argument Clinic now wraps long impl prototypes at column 78.
• Issue #20586: Argument Clinic now ensures that functions without docstrings have signatures.
• Issue #23492: Argument Clinic now generates argument parsing code with PyArg_Parse instead of PyArg_ParseTuple if possible.
• Issue #23500: Argument Clinic is now smarter about generating the “#ifndef” (empty) definition of the methoddef macro: it’s only generated once, even if Argument Clinic processes the same symbol multiple times, and it’s emitted at the end of all processing rather than immediately after the first use.

C API

• Issue #23998: PyImport_ReInitLock() now checks for lock allocation error

Core and Builtins

• Issue #23573: Increased performance of string search operations (str.find, str.index, str.count, the in operator, str.split, str.partition) with arguments of different kinds (UCS1, UCS2, UCS4).
• Issue #23753: Python doesn’t support anymore platforms without stat() or fstat(), these functions are always required.
• Issue #23681: The -b option now affects comparisons of bytes with int.
• Issue #23632: Memoryviews now allow tuple indexing (including for multi-dimensional memoryviews).
• Issue #23192: Fixed generator lambdas. Patch by Bruno Cauet.
• Issue #23629: Fix the default __sizeof__ implementation for variable-sized objects.

Library

• Issue #14260: The groupindex attribute of regular expression pattern object now is non-modifiable mapping.
• Issue #23792: Ignore KeyboardInterrupt when the pydoc pager is active. This mimics the behavior of the standard unix pagers, and prevents pipepager from shutting down while the pager itself is still running.
• Issue #23775: pprint() of OrderedDict now outputs the same representation as repr().
• Issue #23765: Removed IsBadStringPtr calls in ctypes
• Issue #22364: Improved some re error messages using regex for hints.
• Issue #23742: ntpath.expandvars() no longer loses unbalanced single quotes.
• Issue #21717: The zipfile.ZipFile.open function now supports ‘x’ (exclusive creation) mode.
• Issue #21802: The reader in BufferedRWPair now is closed even when closing writer failed in BufferedRWPair.close().
• Issue #23622: Unknown escapes in regular expressions that consist of '\' and ASCII letter now raise a deprecation warning and will be forbidden in Python 3.6.
• Issue #23671: string.Template now allows to specify the “self” parameter as keyword argument. string.Formatter now allows to specify the “self” and the “format_string” parameters as keyword arguments.
• Issue #23502: The pprint module now supports mapping proxies.
• Issue #17530: pprint now wraps long bytes objects and bytearrays.
• Issue #22687: Fixed some corner cases in breaking words in tetxtwrap. Got rid of quadratic complexity in breaking long words.
• Issue #4727: The copy module now uses pickle protocol 4 (PEP 3154) and supports copying of instances of classes whose __new__ method takes keyword-only arguments.
• Issue #23491: Added a zipapp module to support creating executable zip file archives of Python code. Registered ”.pyz” and ”.pyzw” extensions on Windows for these archives (PEP 441).
• Issue #23657: Avoid explicit checks for str in zipapp, adding support for pathlib.Path objects as arguments.
• Issue #23688: Added support of arbitrary bytes-like objects and avoided unnecessary copying of memoryview in gzip.GzipFile.write(). Original patch by Wolfgang Maier.
• Issue #23252: Added support for writing ZIP files to unseekable streams.
• Issue #23647: Increase impalib’s MAXLINE to accommodate modern mailbox sizes.
• Issue #23539: If body is None, http.client.HTTPConnection.request now sets Content-Length to 0 for PUT, POST, and PATCH headers to avoid 411 errors from some web servers.
• Issue #22351: The nntplib.NNTP constructor no longer leaves the connection and socket open until the garbage collector cleans them up. Patch by Martin Panter.
• Issue #23704: collections.deque() objects now support methods for index(), insert(), and copy(). This allows deques to be registered as a MutableSequence and it improves their substitutablity for lists.
• Issue #23715: signal.sigwaitinfo() and signal.sigtimedwait() are now retried when interrupted by a signal not in the sigset parameter, if the signal handler does not raise an exception. signal.sigtimedwait() recomputes the timeout with a monotonic clock when it is retried.
• Issue #23001: Few functions in modules mmap, ossaudiodev, socket, ssl, and codecs, that accepted only read-only bytes-like object now accept writable bytes-like object too.
• Issue #23646: If time.sleep() is interrupted by a signal, the sleep is now retried with the recomputed delay, except if the signal handler raises an exception (PEP 475).
• Issue #23136: _strptime now uniformly handles all days in week 0, including Dec 30 of previous year. Based on patch by Jim Carroll.
• Issue #23700: Iterator of NamedTemporaryFile now keeps a reference to NamedTemporaryFile instance. Patch by Bohuslav Kabrda.
• Issue #22903: The fake test case created by unittest.loader when it fails importing a test module is now picklable.
• Issue #22181: On Linux, os.urandom() now uses the new getrandom() syscall if available, syscall introduced in the Linux kernel 3.17. It is more reliable and more secure, because it avoids the need of a file descriptor and waits until the kernel has enough entropy.
• Issue #2211: Updated the implementation of the http.cookies.Morsel class. Setting attributes key, value and coded_value directly now is deprecated. update() and setdefault() now transform and check keys. Comparing for equality now takes into account attributes key, value and coded_value. copy() now returns a Morsel, not a dict. repr() now contains all attributes. Optimized checking keys and quoting values. Added new tests. Original patch by Demian Brecht.
• Issue #18983: Allow selection of output units in timeit. Patch by Julian Gindi.
• Issue #23631: Fix traceback.format_list when a traceback has been mutated.
• Issue #23568: Add rdivmod support to MagicMock() objects. Patch by Håkan Lövdahl.
• Issue #2052: Add charset parameter to HtmlDiff.make_file().
• Issue #23668: Support os.truncate and os.ftruncate on Windows.
• Issue #23138: Fixed parsing cookies with absent keys or values in cookiejar. Patch by Demian Brecht.
• Issue #23051: multiprocessing.Pool methods imap() and imap_unordered() now handle exceptions raised by an iterator. Patch by Alon Diamant and Davin Potts.
• Issue #23581: Add matmul support to MagicMock. Patch by Håkan Lövdahl.
• Issue #23566: enable(), register(), dump_traceback() and dump_traceback_later() functions of faulthandler now accept file descriptors. Patch by Wei Wu.
• Issue #22928: Disabled HTTP header injections in http.client. Original patch by Demian Brecht.
• Issue #23615: Modules bz2, tarfile and tokenize now can be reloaded with imp.reload(). Patch by Thomas Kluyver.
• Issue #23605: os.walk() now calls os.scandir() instead of os.listdir(). The usage of os.scandir() reduces the number of calls to os.stat(). Initial patch written by Ben Hoyt.

Build

• Issue #23585: make patchcheck will ensure the interpreter is built.

Tests

• Issue #23583: Added tests for standard IO streams in IDLE.
• Issue #22289: Prevent test_urllib2net failures due to ftp connection timeout.

Tools/Demos

• Issue #22826: The result of open() in Tools/freeze/bkfile.py is now better compatible with regular files (in particular it now supports the context management protocol).

Core and Builtins

• Issue #23571: PyObject_Call() and PyCFunction_Call() now raise a SystemError if a function returns a result and raises an exception. The SystemError is chained to the previous exception.

Library

• Issue #22524: New os.scandir() function, part of the PEP 471: “os.scandir() function – a better and faster directory iterator”. Patch written by Ben Hoyt.
• Issue #23103: Reduced the memory consumption of IPv4Address and IPv6Address.
• Issue #21793: BaseHTTPRequestHandler again logs response code as numeric, not as stringified enum. Patch by Demian Brecht.
• Issue #23476: In the ssl module, enable OpenSSL’s X509_V_FLAG_TRUSTED_FIRST flag on certificate stores when it is available.
• Issue #23576: Avoid stalling in SSL reads when EOF has been reached in the SSL layer but the underlying connection hasn’t been closed.
• Issue #23504: Added an __all__ to the types module.
• Issue #23563: Optimized utility functions in urllib.parse.
• Issue #7830: Flatten nested functools.partial.
• Issue #20204: Added the __module__ attribute to _tkinter classes.
• Issue #19980: Improved help() for non-recognized strings. help(‘’) now shows the help on str. help(‘help’) now shows the help on help(). Original patch by Mark Lawrence.
• Issue #23521: Corrected pure python implementation of timedelta division.

• Eliminated OverflowError from timedelta * float for some floats;
• Corrected rounding in timedlta true division.

• Issue #21619: Popen objects no longer leave a zombie after exit in the with statement if the pipe was broken. Patch by Martin Panter.
• Issue #22936: Make it possible to show local variables in tracebacks for both the traceback module and unittest.
• Issue #15955: Add an option to limit the output size in bz2.decompress(). Patch by Nikolaus Rath.
• Issue #6639: Module-level turtle functions no longer raise TclError after closing the window.
• Issues #814253, #9179: Group references and conditional group references now work in lookbehind assertions in regular expressions.
• Issue #23215: Multibyte codecs with custom error handlers that ignores errors consumed too much memory and raised SystemError or MemoryError. Original patch by Aleksi Torhamo.
• Issue #5700: io.FileIO() called flush() after closing the file. flush() was not called in close() if closefd=False.
• Issue #23374: Fixed pydoc failure with non-ASCII files when stdout encoding differs from file system encoding (e.g. on Mac OS).
• Issue #23481: Remove RC4 from the SSL module’s default cipher list.
• Issue #21548: Fix pydoc.synopsis() and pydoc.apropos() on modules with empty docstrings.
• Issue #22885: Fixed arbitrary code execution vulnerability in the dbm.dumb module. Original patch by Claudiu Popa.
• Issue #23239: ssl.match_hostname() now supports matching of IP addresses.
• Issue #23146: Fix mishandling of absolute Windows paths with forward slashes in pathlib.
• Issue #23096: Pickle representation of floats with protocol 0 now is the same for both Python and C implementations.
• Issue #19105: pprint now more efficiently uses free space at the right.
• Issue #14910: Add allow_abbrev parameter to argparse.ArgumentParser. Patch by Jonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson.
• Issue #21717: tarfile.open() now supports ‘x’ (exclusive creation) mode.
• Issue #23344: marshal.dumps() is now 20-25% faster on average.
• Issue #20416: marshal.dumps() with protocols 3 and 4 is now 40-50% faster on average.
• Issue #23421: Fixed compression in tarfile CLI. Patch by wdv4758h.
• Issue #23367: Fix possible overflows in the unicodedata module.
• Issue #23361: Fix possible overflow in Windows subprocess creation code.
• logging.handlers.QueueListener now takes a respect_handler_level keyword argument which, if set to True, will pass messages to handlers taking handler levels into account.
• Issue #19705: turtledemo now has a visual sorting algorithm demo. Original patch from Jason Yeo.
• Issue #23801: Fix issue where cgi.FieldStorage did not always ignore the entire preamble to a multipart body.

Build

• Issue #23445: pydebug builds now use “gcc -Og” where possible, to make the resulting executable faster.
• Issue #23686: Update OS X 10.5 installer build to use OpenSSL 1.0.2a.

C API

• Issue #20204: Deprecation warning is now raised for builtin type without the __module__ attribute.

Windows

• Issue #23465: Implement PEP 486 - Make the Python Launcher aware of virtual environments. Patch by Paul Moore.
• Issue #23437: Make user scripts directory versioned on Windows. Patch by Paul Moore.

Core and Builtins

• Issue #23285: PEP 475 - EINTR handling.
• Issue #22735: Fix many edge cases (including crashes) involving custom mro() implementations.
• Issue #22896: Avoid using PyObject_AsCharBuffer(), PyObject_AsReadBuffer() and PyObject_AsWriteBuffer().
• Issue #21295: Revert some changes (issue #16795) to AST line numbers and column offsets that constituted a regression.
• Issue #22986: Allow changing an object’s __class__ between a dynamic type and static type in some cases.
• Issue #15859: PyUnicode_EncodeFSDefault(), PyUnicode_EncodeMBCS() and PyUnicode_EncodeCodePage() now raise an exception if the object is not an Unicode object. For PyUnicode_EncodeFSDefault(), it was already the case on platforms other than Windows. Patch written by Campbell Barton.
• Issue #21408: The default __ne__() now returns NotImplemented if __eq__() returned NotImplemented. Original patch by Martin Panter.
• Issue #23321: Fixed a crash in str.decode() when error handler returned replacment string longer than mailformed input data.
• Issue #22286: The “backslashreplace” error handlers now works with decoding and translating.
• Issue #23253: Delay-load ShellExecute[AW] in os.startfile for reduced startup overhead on Windows.
• Issue #22038: pyatomic.h now uses stdatomic.h or GCC built-in functions for atomic memory access if available. Patch written by Vitor de Lima and Gustavo Temple.
• Issue #20284: %-interpolation (aka printf) formatting added for bytes and bytearray.
• Issue #23048: Fix jumping out of an infinite while loop in the pdb.
• Issue #20335: bytes constructor now raises TypeError when encoding or errors is specified with non-string argument. Based on patch by Renaud Blanch.
• Issue #22834: If the current working directory ends up being set to a non-existent directory then import will no longer raise FileNotFoundError.
• Issue #22869: Move the interpreter startup & shutdown code to a new dedicated pylifecycle.c module
• Issue #22847: Improve method cache efficiency.
• Issue #22335: Fix crash when trying to enlarge a bytearray to 0x7fffffff bytes on a 32-bit platform.
• Issue #22653: Fix an assertion failure in debug mode when doing a reentrant dict insertion in debug mode.
• Issue #22643: Fix integer overflow in Unicode case operations (upper, lower, title, swapcase, casefold).
• Issue #17636: Circular imports involving relative imports are now supported.
• Issue #22604: Fix assertion error in debug mode when dividing a complex number by (nan+0j).
• Issue #21052: Do not raise ImportWarning when sys.path_hooks or sys.meta_path are set to None.
• Issue #16518: Use ‘bytes-like object required’ in error messages that previously used the far more cryptic “‘x’ does not support the buffer protocol.
• Issue #22470: Fixed integer overflow issues in “backslashreplace”, “xmlcharrefreplace”, and “surrogatepass” error handlers.
• Issue #22540: speed up PyObject_IsInstance and PyObject_IsSubclass in the common case that the second argument has metaclass type.
• Issue #18711: Add a new PyErr_FormatV function, similar to PyErr_Format but accepting a va_list argument.
• Issue #22520: Fix overflow checking when generating the repr of a unicode object.
• Issue #22519: Fix overflow checking in PyBytes_Repr.
• Issue #22518: Fix integer overflow issues in latin-1 encoding.
• Issue #16324: _charset parameter of MIMEText now also accepts email.charset.Charset instances. Initial patch by Claude Paroz.
• Issue #1764286: Fix inspect.getsource() to support decorated functions. Patch by Claudiu Popa.
• Issue #18554: os.__all__ includes posix functions.
• Issue #21391: Use os.path.abspath in the shutil module.
• Issue #11471: avoid generating a JUMP_FORWARD instruction at the end of an if-block if there is no else-clause. Original patch by Eugene Toder.
• Issue #22215: Now ValueError is raised instead of TypeError when str or bytes argument contains not permitted null character or byte.
• Issue #22258: Fix the internal function set_inheritable() on Illumos. This platform exposes the function ioctl(FIOCLEX), but calling it fails with errno is ENOTTY: “Inappropriate ioctl for device”. set_inheritable() now falls back to the slower fcntl() (F_GETFD and then F_SETFD).
• Issue #21389: Displaying the __qualname__ of the underlying function in the repr of a bound method.
• Issue #22206: Using pthread, PyThread_create_key() now sets errno to ENOMEM and returns -1 (error) on integer overflow.
• Issue #20184: Argument Clinic based signature introspection added for 30 of the builtin functions.
• Issue #22116: C functions and methods (of the ‘builtin_function_or_method’ type) can now be weakref’ed. Patch by Wei Wu.
• Issue #22077: Improve index error messages for bytearrays, bytes, lists, and tuples by adding ‘or slices’. Added ‘, not <typename’ for bytearrays. Original patch by Claudiu Popa.
• Issue #20179: Apply Argument Clinic to bytes and bytearray. Patch by Tal Einat.
• Issue #22082: Clear interned strings in slotdefs.
• Upgrade Unicode database to Unicode 7.0.0.
• Issue #21897: Fix a crash with the f_locals attribute with closure variables when frame.clear() has been called.
• Issue #21205: Add a new __qualname__ attribute to generator, the qualified name, and use it in the representation of a generator (repr(gen)). The default name of the generator (__name__ attribute) is now get from the function instead of the code. Use gen.gi_code.co_name to get the name of the code.
• Issue #21669: With the aid of heuristics in SyntaxError.__init__, the parser now attempts to generate more meaningful (or at least more search engine friendly) error messages when “exec” and “print” are used as statements.
• Issue #21642: If the conditional if-else expression, allow an integer written with no space between itself and the else keyword (e.g. True if 42else False) to be valid syntax.
• Issue #21523: Fix over-pessimistic computation of the stack effect of some opcodes in the compiler. This also fixes a quadratic compilation time issue noticeable when compiling code with a large number of “and” and “or” operators.
• Issue #21418: Fix a crash in the builtin function super() when called without argument and without current frame (ex: embedded Python).
• Issue #21425: Fix flushing of standard streams in the interactive interpreter.
• Issue #21435: In rare cases, when running finalizers on objects in cyclic trash a bad pointer dereference could occur due to a subtle flaw in internal iteration logic.
• Issue #21377: PyBytes_Concat() now tries to concatenate in-place when the first argument has a reference count of 1. Patch by Nikolaus Rath.
• Issue #20355: -W command line options now have higher priority than the PYTHONWARNINGS environment variable. Patch by Arfrever.
• Issue #21274: Define PATH_MAX for GNU/Hurd in Python/pythonrun.c.
• Issue #20904: Support setting FPU precision on m68k.
• Issue #21209: Fix sending tuples to custom generator objects with the yield from syntax.
• Issue #21193: pow(a, b, c) now raises ValueError rather than TypeError when b is negative. Patch by Josh Rosenberg.
• PEP 465 and Issue #21176: Add the ‘@’ operator for matrix multiplication.
• Issue #21134: Fix segfault when str is called on an uninitialized UnicodeEncodeError, UnicodeDecodeError, or UnicodeTranslateError object.
• Issue #19537: Fix PyUnicode_DATA() alignment under m68k. Patch by Andreas Schwab.
• Issue #20929: Add a type cast to avoid shifting a negative number.
• Issue #20731: Properly position in source code files even if they are opened in text mode. Patch by Serhiy Storchaka.
• Issue #20637: Key-sharing now also works for instance dictionaries of subclasses. Patch by Peter Ingebretson.
• Issue #8297: Attributes missing from modules now include the module name in the error text. Original patch by ysj.ray.
• Issue #19995: %c, %o, %x, and %X now raise TypeError on non-integer input.
• Issue #19655: The ASDL parser - used by the build process to generate code for managing the Python AST in C - was rewritten. The new parser is self contained and does not require to carry long the spark.py parser-generator library; spark.py was removed from the source base.
• Issue #12546: Allow x00 to be used as a fill character when using str, int, float, and complex __format__ methods.
• Issue #20480: Add ipaddress.reverse_pointer. Patch by Leon Weber.
• Issue #13598: Modify string.Formatter to support auto-numbering of replacement fields. It now matches the behavior of str.format() in this regard. Patches by Phil Elson and Ramchandra Apte.
• Issue #8931: Make alternate formatting (‘#’) for type ‘c’ raise an exception. In versions prior to 3.5, ‘#’ with ‘c’ had no effect. Now specifying it is an error. Patch by Torsten Landschoff.
• Issue #23165: Perform overflow checks before allocating memory in the _Py_char2wchar function.

Library

• Issue #23399: pyvenv creates relative symlinks where possible.
• Issue #20289: cgi.FieldStorage() now supports the context management protocol.
• Issue #13128: Print response headers for CONNECT requests when debuglevel > 0. Patch by Demian Brecht.
• Issue #15381: Optimized io.BytesIO to make less allocations and copyings.
• Issue #22818: Splitting on a pattern that could match an empty string now raises a warning. Patterns that can only match empty strings are now rejected.
• Issue #23099: Closing io.BytesIO with exported buffer is rejected now to prevent corrupting exported buffer.
• Issue #23326: Removed __ne__ implementations. Since fixing default __ne__ implementation in issue #21408 they are redundant.
• Issue #23363: Fix possible overflow in itertools.permutations.
• Issue #23364: Fix possible overflow in itertools.product.
• Issue #23366: Fixed possible integer overflow in itertools.combinations.
• Issue #23369: Fixed possible integer overflow in _json.encode_basestring_ascii.
• Issue #23353: Fix the exception handling of generators in PyEval_EvalFrameEx(). At entry, save or swap the exception state even if PyEval_EvalFrameEx() is called with throwflag=0. At exit, the exception state is now always restored or swapped, not only if why is WHY_YIELD or WHY_RETURN. Patch co-written with Antoine Pitrou.
• Issue #14099: Restored support of writing ZIP files to tellable but non-seekable streams.
• Issue #14099: Writing to ZipFile and reading multiple ZipExtFiles is threadsafe now.
• Issue #19361: JSON decoder now raises JSONDecodeError instead of ValueError.
• Issue #18518: timeit now rejects statements which can’t be compiled outside a function or a loop (e.g. “return” or “break”).
• Issue #23094: Fixed readline with frames in Python implementation of pickle.
• Issue #23268: Fixed bugs in the comparison of ipaddress classes.
• Issue #21408: Removed incorrect implementations of __ne__() which didn’t returned NotImplemented if __eq__() returned NotImplemented. The default __ne__() now works correctly.
• Issue #19996: email.feedparser.FeedParser now handles (malformed) headers with no key rather than assuming the body has started.
• Issue #20188: Support Application-Layer Protocol Negotiation (ALPN) in the ssl module.
• Issue #23133: Pickling of ipaddress objects now produces more compact and portable representation.
• Issue #23248: Update ssl error codes from latest OpenSSL git master.
• Issue #23266: Much faster implementation of ipaddress.collapse_addresses() when there are many non-consecutive addresses.
• Issue #23098: 64-bit dev_t is now supported in the os module.
• Issue #21817: When an exception is raised in a task submitted to a ProcessPoolExecutor, the remote traceback is now displayed in the parent process. Patch by Claudiu Popa.
• Issue #15955: Add an option to limit output size when decompressing LZMA data. Patch by Nikolaus Rath and Martin Panter.
• Issue #23250: In the http.cookies module, capitalize “HttpOnly” and “Secure” as they are written in the standard.
• Issue #23063: In the disutils’ check command, fix parsing of reST with code or code-block directives.
• Issue #23209, #23225: selectors.BaseSelector.get_key() now raises a RuntimeError if the selector is closed. And selectors.BaseSelector.close() now clears its internal reference to the selector mapping to break a reference cycle. Initial patch written by Martin Richard.
• Issue #17911: Provide a way to seed the linecache for a PEP-302 module without actually loading the code.
• Issue #17911: Provide a new object API for traceback, including the ability to not lookup lines at all until the traceback is actually rendered, without any trace of the original objects being kept alive.
• Issue #19777: Provide a home() classmethod on Path objects. Contributed by Victor Salgado and Mayank Tripathi.
• Issue #23206: Make json.dumps(..., ensure_ascii=False) as fast as the default case of ensure_ascii=True. Patch by Naoki Inada.
• Issue #23185: Add math.inf and math.nan constants.
• Issue #23186: Add ssl.SSLObject.shared_ciphers() and ssl.SSLSocket.shared_ciphers() to fetch the client’s list ciphers sent at handshake.
• Issue #23143: Remove compatibility with OpenSSLs older than 0.9.8.
• Issue #23132: Improve performance and introspection support of comparison methods created by functool.total_ordering.
• Issue #19776: Add a expanduser() method on Path objects.
• Issue #23112: Fix SimpleHTTPServer to correctly carry the query string and fragment when it redirects to add a trailing slash.
• Issue #21793: Added http.HTTPStatus enums (i.e. HTTPStatus.OK, HTTPStatus.NOT_FOUND). Patch by Demian Brecht.
• Issue #23093: In the io, module allow more operations to work on detached streams.
• Issue #23111: In the ftplib, make ssl.PROTOCOL_SSLv23 the default protocol version.
• Issue #22585: On OpenBSD 5.6 and newer, os.urandom() now calls getentropy(), instead of reading /dev/urandom, to get pseudo-random bytes.
• Issue #19104: pprint now produces evaluable output for wrapped strings.
• Issue #23071: Added missing names to codecs.__all__. Patch by Martin Panter.
• Issue #22783: Pickling now uses the NEWOBJ opcode instead of the NEWOBJ_EX opcode if possible.
• Issue #15513: Added a __sizeof__ implementation for pickle classes.
• Issue #19858: pickletools.optimize() now aware of the MEMOIZE opcode, can produce more compact result and no longer produces invalid output if input data contains MEMOIZE opcodes together with PUT or BINPUT opcodes.
• Issue #22095: Fixed HTTPConnection.set_tunnel with default port. The port value in the host header was set to “None”. Patch by Demian Brecht.
• Issue #23016: A warning no longer produces an AttributeError when the program is run with pythonw.exe.
• Issue #21775: shutil.copytree(): fix crash when copying to VFAT. An exception handler assumed that that OSError objects always have a ‘winerror’ attribute. That is not the case, so the exception handler itself raised AttributeError when run on Linux (and, presumably, any other non-Windows OS). Patch by Greg Ward.
• Issue #1218234: Fix inspect.getsource() to load updated source of reloaded module. Initial patch by Berker Peksag.
• Issue #21740: Support wrapped callables in doctest. Patch by Claudiu Popa.
• Issue #23009: Make sure selectors.EpollSelecrtor.select() works when no FD is registered.
• Issue #22959: In the constructor of http.client.HTTPSConnection, prefer the context’s check_hostname attribute over the check_hostname parameter.
• Issue #22696: Add function sys.is_finalizing() to know about interpreter shutdown.
• Issue #16043: Add a default limit for the amount of data xmlrpclib.gzip_decode will return. This resolves CVE-2013-1753.
• Issue #14099: ZipFile.open() no longer reopen the underlying file. Objects returned by ZipFile.open() can now operate independently of the ZipFile even if the ZipFile was created by passing in a file-like object as the first argument to the constructor.
• Issue #22966: Fix __pycache__ pyc file name clobber when pyc_compile is asked to compile a source file containing multiple dots in the source file name.
• Issue #21971: Update turtledemo doc and add module to the index.
• Issue #21032. Fixed socket leak if HTTPConnection.getresponse() fails. Original patch by Martin Panter.
• Issue #22407: Deprecated the use of re.LOCALE flag with str patterns or re.ASCII. It was newer worked.
• Issue #22902: The “ip” command is now used on Linux to determine MAC address in uuid.getnode(). Pach by Bruno Cauet.
• Issue #22960: Add a context argument to xmlrpclib.ServerProxy constructor.
• Issue #22389: Add contextlib.redirect_stderr().
• Issue #21356: Make ssl.RAND_egd() optional to support LibreSSL. The availability of the function is checked during the compilation. Patch written by Bernard Spil.
• Issue #22915: SAX parser now supports files opened with file descriptor or bytes path.
• Issue #22609: Constructors and update methods of mapping classes in the collections module now accept the self keyword argument.
• Issue #22940: Add readline.append_history_file.
• Issue #19676: Added the “namereplace” error handler.
• Issue #22788: Add context parameter to logging.handlers.HTTPHandler.
• Issue #22921: Allow SSLContext to take the hostname parameter even if OpenSSL doesn’t support SNI.
• Issue #22894: TestCase.subTest() would cause the test suite to be stopped when in failfast mode, even in the absence of failures.
• Issue #22796: HTTP cookie parsing is now stricter, in order to protect against potential injection attacks.
• Issue #22370: Windows detection in pathlib is now more robust.
• Issue #22841: Reject coroutines in asyncio add_signal_handler(). Patch by Ludovic.Gasc.
• Issue #19494: Added urllib.request.HTTPBasicPriorAuthHandler. Patch by Matej Cepl.
• Issue #22578: Added attributes to the re.error class.
• Issue #22849: Fix possible double free in the io.TextIOWrapper constructor.
• Issue #12728: Different Unicode characters having the same uppercase but different lowercase are now matched in case-insensitive regular expressions.
• Issue #22821: Fixed fcntl() with integer argument on 64-bit big-endian platforms.
• Issue #21650: Add an --sort-keys option to json.tool CLI.
• Issue #22824: Updated reprlib output format for sets to use set literals. Patch contributed by Berker Peksag.
• Issue #22824: Updated reprlib output format for arrays to display empty arrays without an unnecessary empty list. Suggested by Serhiy Storchaka.
• Issue #22406: Fixed the uu_codec codec incorrectly ported to 3.x. Based on patch by Martin Panter.
• Issue #17293: uuid.getnode() now determines MAC address on AIX using netstat. Based on patch by Aivars Kalvāns.
• Issue #22769: Fixed ttk.Treeview.tag_has() when called without arguments.
• Issue #22417: Verify certificates by default in httplib (PEP 476).
• Issue #22775: Fixed unpickling of http.cookies.SimpleCookie with protocol 2 and above. Patch by Tim Graham.
• Issue #22776: Brought excluded code into the scope of a try block in SysLogHandler.emit().
• Issue #22665: Add missing get_terminal_size and SameFileError to shutil.__all__.
• Issue #6623: Remove deprecated Netrc class in the ftplib module. Patch by Matt Chaput.
• Issue #17381: Fixed handling of case-insensitive ranges in regular expressions.
• Issue #22410: Module level functions in the re module now cache compiled locale-dependent regular expressions taking into account the locale.
• Issue #22759: Query methods on pathlib.Path() (exists(), is_dir(), etc.) now return False when the underlying stat call raises NotADirectoryError.
• Issue #8876: distutils now falls back to copying files when hard linking doesn’t work. This allows use with special filesystems such as VirtualBox shared folders.
• Issue #22217: Implemented reprs of classes in the zipfile module.
• Issue #22457: Honour load_tests in the start_dir of discovery.
• Issue #18216: gettext now raises an error when a .mo file has an unsupported major version number. Patch by Aaron Hill.
• Issue #13918: Provide a locale.delocalize() function which can remove locale-specific number formatting from a string representing a number, without then converting it to a specific type. Patch by Cédric Krier.
• Issue #22676: Make the pickling of global objects which don’t have a __module__ attribute less slow.
• Issue #18853: Fixed ResourceWarning in shlex.__nain__.
• Issue #9351: Defaults set with set_defaults on an argparse subparser are no longer ignored when also set on the parent parser.
• Issue #7559: unittest test loading ImportErrors are reported as import errors with their import exception rather than as attribute errors after the import has already failed.
• Issue #19746: Make it possible to examine the errors from unittest discovery without executing the test suite. The new errors attribute on TestLoader exposes these non-fatal errors encountered during discovery.
• Issue #21991: Make email.headerregistry’s header ‘params’ attributes be read-only (MappingProxyType). Previously the dictionary was modifiable but a new one was created on each access of the attribute.
• Issue #22638: SSLv3 is now disabled throughout the standard library. It can still be enabled by instantiating a SSLContext manually.
• Issue #22641: In asyncio, the default SSL context for client connections is now created using ssl.create_default_context(), for stronger security.
• Issue #17401: Include closefd in io.FileIO repr.
• Issue #21338: Add silent mode for compileall. quiet parameters of compile_{dir, file, path} functions now have a multilevel value. Also, -q option of the CLI now have a multilevel value. Patch by Thomas Kluyver.
• Issue #20152: Convert the array and cmath modules to Argument Clinic.
• Issue #18643: Add socket.socketpair() on Windows.
• Issue #22435: Fix a file descriptor leak when SocketServer bind fails.
• Issue #13096: Fixed segfault in CTypes POINTER handling of large values.
• Issue #11694: Raise ConversionError in xdrlib as documented. Patch by Filip Gruszczyński and Claudiu Popa.
• Issue #19380: Optimized parsing of regular expressions.
• Issue #1519638: Now unmatched groups are replaced with empty strings in re.sub() and re.subn().
• Issue #18615: sndhdr.what/whathdr now return a namedtuple.
• Issue #22462: Fix pyexpat’s creation of a dummy frame to make it appear in exception tracebacks.
• Issue #21965: Add support for in-memory SSL to the ssl module. Patch by Geert Jansen.
• Issue #21173: Fix len() on a WeakKeyDictionary when .clear() was called with an iterator alive.
• Issue #11866: Eliminated race condition in the computation of names for new threads.
• Issue #21905: Avoid RuntimeError in pickle.whichmodule() when sys.modules is mutated while iterating. Patch by Olivier Grisel.
• Issue #11271: concurrent.futures.Executor.map() now takes a chunksize argument to allow batching of tasks in child processes and improve performance of ProcessPoolExecutor. Patch by Dan O’Reilly.
• Issue #21883: os.path.join() and os.path.relpath() now raise a TypeError with more helpful error message for unsupported or mismatched types of arguments.
• Issue #22219: The zipfile module CLI now adds entries for directories (including empty directories) in ZIP file.
• Issue #22449: In the ssl.SSLContext.load_default_certs, consult the environmental variables SSL_CERT_DIR and SSL_CERT_FILE on Windows.
• Issue #22508: The email.__version__ variable has been removed; the email code is no longer shipped separately from the stdlib, and __version__ hasn’t been updated in several releases.
• Issue #20076: Added non derived UTF-8 aliases to locale aliases table.
• Issue #20079: Added locales supported in glibc 2.18 to locale alias table.
• Issue #20218: Added convenience methods read_text/write_text and read_bytes/ write_bytes to pathlib.Path objects.
• Issue #22437: Number of capturing groups in regular expression is no longer limited by 100.
• Issue #17442: InteractiveInterpreter now displays the full chained traceback in its showtraceback method, to match the built in interactive interpreter.
• Issue #23392: Added tests for marshal C API that works with FILE*.
• Issue #10510: distutils register and upload methods now use HTML standards compliant CRLF line endings.
• Issue #9850: Fixed macpath.join() for empty first component. Patch by Oleg Oshmyan.
• Issue #5309: distutils’ build and build_ext commands now accept a -j option to enable parallel building of extension modules.
• Issue #22448: Improve canceled timer handles cleanup to prevent unbound memory usage. Patch by Joshua Moore-Oliva.
• Issue #22427: TemporaryDirectory no longer attempts to clean up twice when used in the with statement in generator.
• Issue #22362: Forbidden ambiguous octal escapes out of range 0-0o377 in regular expressions.
• Issue #20912: Now directories added to ZIP file have correct Unix and MS-DOS directory attributes.
• Issue #21866: ZipFile.close() no longer writes ZIP64 central directory records if allowZip64 is false.
• Issue #22278: Fix urljoin problem with relative urls, a regression observed after changes to issue22118 were submitted.
• Issue #22415: Fixed debugging output of the GROUPREF_EXISTS opcode in the re module. Removed trailing spaces in debugging output.
• Issue #22423: Unhandled exception in thread no longer causes unhandled AttributeError when sys.stderr is None.
• Issue #21332: Ensure that bufsize=1 in subprocess.Popen() selects line buffering, rather than block buffering. Patch by Akira Li.
• Issue #21091: Fix API bug: email.message.EmailMessage.is_attachment is now a method.
• Issue #21079: Fix email.message.EmailMessage.is_attachment to return the correct result when the header has parameters as well as a value.
• Issue #22247: Add NNTPError to nntplib.__all__.
• Issue #22366: urllib.request.urlopen will accept a context object (SSLContext) as an argument which will then used be for HTTPS connection. Patch by Alex Gaynor.
• Issue #4180: The warnings registries are now reset when the filters are modified.
• Issue #22419: Limit the length of incoming HTTP request in wsgiref server to 65536 bytes and send a 414 error code for higher lengths. Patch contributed by Devin Cook.
• Lax cookie parsing in http.cookies could be a security issue when combined with non-standard cookie handling in some Web browsers. Reported by Sergey Bobrov.
• Issue #20537: logging methods now accept an exception instance as well as a Boolean value or exception tuple. Thanks to Yury Selivanov for the patch.
• Issue #22384: An exception in Tkinter callback no longer crashes the program when it is run with pythonw.exe.
• Issue #22168: Prevent turtle AttributeError with non-default Canvas on OS X.
• Issue #21147: sqlite3 now raises an exception if the request contains a null character instead of truncate it. Based on patch by Victor Stinner.
• Issue #13968: The glob module now supports recursive search in subdirectories using the “**” pattern.
• Issue #21951: Fixed a crash in Tkinter on AIX when called Tcl command with empty string or tuple argument.
• Issue #21951: Tkinter now most likely raises MemoryError instead of crash if the memory allocation fails.
• Issue #22338: Fix a crash in the json module on memory allocation failure.
• Issue #12410: imaplib.IMAP4 now supports the context management protocol. Original patch by Tarek Ziadé.
• Issue #21270: We now override tuple methods in mock.call objects so that they can be used as normal call attributes.
• Issue #16662: load_tests() is now unconditionally run when it is present in a package’s __init__.py. TestLoader.loadTestsFromModule() still accepts use_load_tests, but it is deprecated and ignored. A new keyword-only attribute pattern is added and documented. Patch given by Robert Collins, tweaked by Barry Warsaw.
• Issue #22226: First letter no longer is stripped from the “status” key in the result of Treeview.heading().
• Issue #19524: Fixed resource leak in the HTTP connection when an invalid response is received. Patch by Martin Panter.
• Issue #20421: Add a .version() method to SSL sockets exposing the actual protocol version in use.
• Issue #19546: configparser exceptions no longer expose implementation details. Chained KeyErrors are removed, which leads to cleaner tracebacks. Patch by Claudiu Popa.
• Issue #22051: turtledemo no longer reloads examples to re-run them. Initialization of variables and gui setup should be done in main(), which is called each time a demo is run, but not on import.
• Issue #21933: Turtledemo users can change the code font size with a menu selection or control(command) ‘-‘ or ‘+’ or control-mousewheel. Original patch by Lita Cho.
• Issue #21597: The separator between the turtledemo text pane and the drawing canvas can now be grabbed and dragged with a mouse. The code text pane can be widened to easily view or copy the full width of the text. The canvas can be widened on small screens. Original patches by Jan Kanis and Lita Cho.
• Issue #18132: Turtledemo buttons no longer disappear when the window is shrunk. Original patches by Jan Kanis and Lita Cho.
• Issue #22043: time.monotonic() is now always available. threading.Lock.acquire(), threading.RLock.acquire() and socket operations now use a monotonic clock, instead of the system clock, when a timeout is used.
• Issue #21527: Add a default number of workers to ThreadPoolExecutor equal to 5 times the number of CPUs. Patch by Claudiu Popa.
• Issue #22216: smtplib now resets its state more completely after a quit. The most obvious consequence of the previous behavior was a STARTTLS failure during a connect/starttls/quit/connect/starttls sequence.
• Issue #22098: ctypes’ BigEndianStructure and LittleEndianStructure now define an empty __slots__ so that subclasses don’t always get an instance dict. Patch by Claudiu Popa.
• Issue #22185: Fix an occasional RuntimeError in threading.Condition.wait() caused by mutation of the waiters queue without holding the lock. Patch by Doug Zongker.
• Issue #22287: On UNIX, _PyTime_gettimeofday() now uses clock_gettime(CLOCK_REALTIME) if available. As a side effect, Python now depends on the librt library on Solaris and on Linux (only with glibc older than 2.17).
• Issue #22182: Use e.args to unpack exceptions correctly in distutils.file_util.move_file. Patch by Claudiu Popa.
• The webbrowser module now uses subprocess’s start_new_session=True rather than a potentially risky preexec_fn=os.setsid call.
• Issue #22042: signal.set_wakeup_fd(fd) now raises an exception if the file descriptor is in blocking mode.
• Issue #16808: inspect.stack() now returns a named tuple instead of a tuple. Patch by Daniel Shahaf.
• Issue #22236: Fixed Tkinter images copying operations in NoDefaultRoot mode.
• Issue #2527: Add a globals argument to timeit functions, in order to override the globals namespace in which the timed code is executed. Patch by Ben Roberts.
• Issue #22118: Switch urllib.parse to use RFC 3986 semantics for the resolution of relative URLs, rather than RFCs 1808 and 2396. Patch by Demian Brecht.
• Issue #21549: Added the “members” parameter to TarFile.list().
• Issue #19628: Allow compileall recursion depth to be specified with a -r option.
• Issue #15696: Add a __sizeof__ implementation for mmap objects on Windows.
• Issue #22068: Avoided reference loops with Variables and Fonts in Tkinter.
• Issue #22165: SimpleHTTPRequestHandler now supports undecodable file names.
• Issue #15381: Optimized line reading in io.BytesIO.
• Issue #8797: Raise HTTPError on failed Basic Authentication immediately. Initial patch by Sam Bull.
• Issue #20729: Restored the use of lazy iterkeys()/itervalues()/iteritems() in the mailbox module.
• Issue #21448: Changed FeedParser feed() to avoid O(N**2) behavior when parsing long line. Original patch by Raymond Hettinger.
• Issue #22184: The functools LRU Cache decorator factory now gives an earlier and clearer error message when the user forgets the required parameters.
• Issue #17923: glob() patterns ending with a slash no longer match non-dirs on AIX. Based on patch by Delhallt.
• Issue #21725: Added support for RFC 6531 (SMTPUTF8) in smtpd.
• Issue #22176: Update the ctypes module’s libffi to v3.1. This release adds support for the Linux AArch64 and POWERPC ELF ABIv2 little endian architectures.
• Issue #5411: Added support for the “xztar” format in the shutil module.
• Issue #21121: Don’t force 3rd party C extensions to be built with -Werror=declaration-after-statement.
• Issue #21975: Fixed crash when using uninitialized sqlite3.Row (in particular when unpickling pickled sqlite3.Row). sqlite3.Row is now initialized in the __new__() method.
• Issue #20170: Convert posixmodule to use Argument Clinic.
• Issue #21539: Add a exists_ok argument to Pathlib.mkdir() to mimic mkdir -p and os.makedirs() functionality. When true, ignore FileExistsErrors. Patch by Berker Peksag.
• Issue #22127: Bypass IDNA for pure-ASCII host names in the socket module (in particular for numeric IPs).
• Issue #21047: set the default value for the convert_charrefs argument of HTMLParser to True. Patch by Berker Peksag.
• Add an __all__ to html.entities.
• Issue #15114: the strict mode and argument of HTMLParser, HTMLParser.error, and the HTMLParserError exception have been removed.
• Issue #22085: Dropped support of Tk 8.3 in Tkinter.
• Issue #21580: Now Tkinter correctly handles bytes arguments passed to Tk. In particular this allows to initialize images from binary data.
• Issue #22003: When initialized from a bytes object, io.BytesIO() now defers making a copy until it is mutated, improving performance and memory use on some use cases. Patch by David Wilson.
• Issue #22018: On Windows, signal.set_wakeup_fd() now also supports sockets. A side effect is that Python depends to the WinSock library.
• Issue #22054: Add os.get_blocking() and os.set_blocking() functions to get and set the blocking mode of a file descriptor (False if the O_NONBLOCK flag is set, True otherwise). These functions are not available on Windows.
• Issue #17172: Make turtledemo start as active on OS X even when run with subprocess. Patch by Lita Cho.
• Issue #21704: Fix build error for _multiprocessing when semaphores are not available. Patch by Arfrever Frehtes Taifersar Arahesis.
• Issue #20173: Convert sha1, sha256, sha512 and md5 to ArgumentClinic. Patch by Vajrasky Kok.
• Fix repr(_socket.socket) on Windows 64-bit: don’t fail with OverflowError on closed socket. repr(socket.socket) already works fine.
• Issue #22033: Reprs of most Python implemened classes now contain actual class name instead of hardcoded one.
• Issue #21947: The dis module can now disassemble generator-iterator objects based on their gi_code attribute. Patch by Clement Rouault.
• Issue #16133: The asynchat.async_chat.handle_read() method now ignores BlockingIOError exceptions.
• Issue #22044: Fixed premature DECREF in call_tzinfo_method. Patch by Tom Flanagan.
• Issue #19884: readline: Disable the meta modifier key if stdout is not a terminal to not write the ANSI sequence “033[1034h” into stdout. This sequence is used on some terminal (ex: TERM=xterm-256color”) to enable support of 8 bit characters.
• Issue #4350: Removed a number of out-of-dated and non-working for a long time Tkinter methods.
• Issue #6167: Scrollbar.activate() now returns the name of active element if the argument is not specified. Scrollbar.set() now always accepts only 2 arguments.
• Issue #15275: Clean up and speed up the ntpath module.
• Issue #21888: plistlib’s load() and loads() now work if the fmt parameter is specified.
• Issue #22032: __qualname__ instead of __name__ is now always used to format fully qualified class names of Python implemented classes.
• Issue #22031: Reprs now always use hexadecimal format with the “0x” prefix when contain an id in form ” at 0x...”.
• Issue #22018: signal.set_wakeup_fd() now raises an OSError instead of a ValueError on fstat() failure.
• Issue #21044: tarfile.open() now handles fileobj with an integer ‘name’ attribute. Based on patch by Antoine Pietri.
• Issue #21966: Respect -q command-line option when code module is ran.
• Issue #19076: Don’t pass the redundant ‘file’ argument to self.error().
• Issue #16382: Improve exception message of warnings.warn() for bad category. Initial patch by Phil Elson.
• Issue #21932: os.read() now uses a Py_ssize_t() type instead of int for the size to support reading more than 2 GB at once. On Windows, the size is truncted to INT_MAX. As any call to os.read(), the OS may read less bytes than the number of requested bytes.
• Issue #21942: Fixed source file viewing in pydoc’s server mode on Windows.
• Issue #11259: asynchat.async_chat().set_terminator() now raises a ValueError if the number of received bytes is negative.
• Issue #12523: asynchat.async_chat.push() now raises a TypeError if it doesn’t get a bytes string
• Issue #21707: Add missing kwonlyargcount argument to ModuleFinder.replace_paths_in_code().
• Issue #20639: calling Path.with_suffix(‘’) allows removing the suffix again. Patch by July Tikhonov.
• Issue #21714: Disallow the construction of invalid paths using Path.with_name(). Original patch by Antony Lee.
• Issue #15014: Added ‘auth’ method to smtplib to make implementing auth mechanisms simpler, and used it internally in the login method.
• Issue #21151: Fixed a segfault in the winreg module when None is passed as a REG_BINARY value to SetValueEx. Patch by John Ehresman.
• Issue #21090: io.FileIO.readall() does not ignore I/O errors anymore. Before, it ignored I/O errors if at least the first C call read() succeed.
• Issue #5800: headers parameter of wsgiref.headers.Headers is now optional. Initial patch by Pablo Torres Navarrete and SilentGhost.
• Issue #21781: ssl.RAND_add() now supports strings longer than 2 GB.
• Issue #21679: Prevent extraneous fstat() calls during open(). Patch by Bohuslav Kabrda.
• Issue #21863: cProfile now displays the module name of C extension functions, in addition to their own name.
• Issue #11453: asyncore: emit a ResourceWarning when an unclosed file_wrapper object is destroyed. The destructor now closes the file if needed. The close() method can now be called twice: the second call does nothing.
• Issue #21858: Better handling of Python exceptions in the sqlite3 module.
• Issue #21476: Make sure the email.parser.BytesParser TextIOWrapper is discarded after parsing, so the input file isn’t unexpectedly closed.
• Issue #20295: imghdr now recognizes OpenEXR format images.
• Issue #21729: Used the “with” statement in the dbm.dumb module to ensure files closing. Patch by Claudiu Popa.
• Issue #21491: socketserver: Fix a race condition in child processes reaping.
• Issue #21719: Added the st_file_attributes field to os.stat_result on Windows.
• Issue #21832: Require named tuple inputs to be exact strings.
• Issue #21722: The distutils “upload” command now exits with a non-zero return code when uploading fails. Patch by Martin Dengler.
• Issue #21723: asyncio.Queue: support any type of number (ex: float) for the maximum size. Patch written by Vajrasky Kok.
• Issue #21711: support for “site-python” directories has now been removed from the site module (it was deprecated in 3.4).
• Issue #17552: new socket.sendfile() method allowing to send a file over a socket by using high-performance os.sendfile() on UNIX. Patch by Giampaolo Rodola’.
• Issue #18039: dbm.dump.open() now always creates a new database when the flag has the value ‘n’. Patch by Claudiu Popa.
• Issue #21326: Add a new is_closed() method to asyncio.BaseEventLoop. run_forever() and run_until_complete() methods of asyncio.BaseEventLoop now raise an exception if the event loop was closed.
• Issue #21766: Prevent a security hole in CGIHTTPServer by URL unquoting paths before checking for a CGI script at that path.
• Issue #21310: Fixed possible resource leak in failed open().
• Issue #21256: Printout of keyword args should be in deterministic order in a mock function call. This will help to write better doctests.
• Issue #21677: Fixed chaining nonnormalized exceptions in io close() methods.
• Issue #11709: Fix the pydoc.help function to not fail when sys.stdin is not a valid file.
• Issue #21515: tempfile.TemporaryFile now uses os.O_TMPFILE flag is available.
• Issue #13223: Fix pydoc.writedoc so that the HTML documentation for methods that use ‘self’ in the example code is generated correctly.
• Issue #21463: In urllib.request, fix pruning of the FTP cache.
• Issue #21618: The subprocess module could fail to close open fds that were inherited by the calling process and already higher than POSIX resource limits would otherwise allow. On systems with a functioning /proc/self/fd or /dev/fd interface the max is now ignored and all fds are closed.
• Issue #20383: Introduce importlib.util.module_from_spec() as the preferred way to create a new module.
• Issue #21552: Fixed possible integer overflow of too long string lengths in the tkinter module on 64-bit platforms.
• Issue #14315: The zipfile module now ignores extra fields in the central directory that are too short to be parsed instead of letting a struct.unpack error bubble up as this “bad data” appears in many real world zip files in the wild and is ignored by other zip tools.
• Issue #13742: Added “key” and “reverse” parameters to heapq.merge(). (First draft of patch contributed by Simon Sapin.)
• Issue #21402: tkinter.ttk now works when default root window is not set.
• Issue #3015: _tkinter.create() now creates tkapp object with wantobject=1 by default.
• Issue #10203: sqlite3.Row now truly supports sequence protocol. In particulr it supports reverse() and negative indices. Original patch by Claudiu Popa.
• Issue #18807: If copying (no symlinks) specified for a venv, then the python interpreter aliases (python, python3) are now created by copying rather than symlinking.
• Issue #20197: Added support for the WebP image type in the imghdr module. Patch by Fabrice Aneche and Claudiu Popa.
• Issue #21513: Speedup some properties of IP addresses (IPv4Address, IPv6Address) such as .is_private or .is_multicast.
• Issue #21137: Improve the repr for threading.Lock() and its variants by showing the “locked” or “unlocked” status. Patch by Berker Peksag.
• Issue #21538: The plistlib module now supports loading of binary plist files when reference or offset size is not a power of two.
• Issue #21455: Add a default backlog to socket.listen().
• Issue #21525: Most Tkinter methods which accepted tuples now accept lists too.
• Issue #22166: With the assistance of a new internal _codecs._forget_codec helping function, test_codecs now clears the encoding caches to avoid the appearance of a reference leak
• Issue #22236: Tkinter tests now don’t reuse default root window. New root window is created for every test class.
• Issue #10744: Fix PEP 3118 format strings on ctypes objects with a nontrivial shape.
• Issue #20826: Optimize ipaddress.collapse_addresses().
• Issue #21487: Optimize ipaddress.summarize_address_range() and ipaddress.{IPv4Network,IPv6Network}.subnets().
• Issue #21486: Optimize parsing of netmasks in ipaddress.IPv4Network and ipaddress.IPv6Network.
• Issue #13916: Disallowed the surrogatepass error handler for non UTF-* encodings.
• Issue #20998: Fixed re.fullmatch() of repeated single character pattern with ignore case. Original patch by Matthew Barnett.
• Issue #21075: fileinput.FileInput now reads bytes from standard stream if binary mode is specified. Patch by Sam Kimbrel.
• Issue #19775: Add a samefile() method to pathlib Path objects. Initial patch by Vajrasky Kok.
• Issue #21226: Set up modules properly in PyImport_ExecCodeModuleObject (and friends).
• Issue #21398: Fix an unicode error in the pydoc pager when the documentation contains characters not encodable to the stdout encoding.
• Issue #16531: ipaddress.IPv4Network and ipaddress.IPv6Network now accept an (address, netmask) tuple argument, so as to easily construct network objects from existing addresses.
• Issue #21156: importlib.abc.InspectLoader.source_to_code() is now a staticmethod.
• Issue #21424: Simplified and optimized heaqp.nlargest() and nmsmallest() to make fewer tuple comparisons.
• Issue #21396: Fix TextIOWrapper(..., write_through=True) to not force a flush() on the underlying binary stream. Patch by akira.
• Issue #18314: Unlink now removes junctions on Windows. Patch by Kim Gräsman
• Issue #21088: Bugfix for curses.window.addch() regression in 3.4.0. In porting to Argument Clinic, the first two arguments were reversed.
• Issue #21407: _decimal: The module now supports function signatures.
• Issue #10650: Remove the non-standard ‘watchexp’ parameter from the Decimal.quantize() method in the Python version. It had never been present in the C version.
• Issue #21469: Reduced the risk of false positives in robotparser by checking to make sure that robots.txt has been read or does not exist prior to returning True in can_fetch().
• Issue #19414: Have the OrderedDict mark deleted links as unusable. This gives an early failure if the link is deleted during iteration.
• Issue #21421: Add __slots__ to the MappingViews ABC. Patch by Josh Rosenberg.
• Issue #21101: Eliminate double hashing in the C speed-up code for collections.Counter().
• Issue #21321: itertools.islice() now releases the reference to the source iterator when the slice is exhausted. Patch by Anton Afanasyev.
• Issue #21057: TextIOWrapper now allows the underlying binary stream’s read() or read1() method to return an arbitrary bytes-like object (such as a memoryview). Patch by Nikolaus Rath.
• Issue #20951: SSLSocket.send() now raises either SSLWantReadError or SSLWantWriteError on a non-blocking socket if the operation would block. Previously, it would return 0. Patch by Nikolaus Rath.
• Issue #13248: removed previously deprecated asyncore.dispatcher __getattr__ cheap inheritance hack.
• Issue #9815: assertRaises now tries to clear references to local variables in the exception’s traceback.
• Issue #19940: ssl.cert_time_to_seconds() now interprets the given time string in the UTC timezone (as specified in RFC 5280), not the local timezone.
• Issue #13204: Calling sys.flags.__new__ would crash the interpreter, now it raises a TypeError.
• Issue #19385: Make operations on a closed dbm.dumb database always raise the same exception.
• Issue #21207: Detect when the os.urandom cached fd has been closed or replaced, and open it anew.
• Issue #21291: subprocess’s Popen.wait() is now thread safe so that multiple threads may be calling wait() or poll() on a Popen instance at the same time without losing the Popen.returncode value.
• Issue #21127: Path objects can now be instantiated from str subclass instances (such as numpy.str_).
• Issue #15002: urllib.response object to use _TemporaryFileWrapper (and _TemporaryFileCloser) facility. Provides a better way to handle file descriptor close. Patch contributed by Christian Theune.
• Issue #12220: mindom now raises a custom ValueError indicating it doesn’t support spaces in URIs instead of letting a ‘split’ ValueError bubble up.
• Issue #21068: The ssl.PROTOCOL* constants are now enum members.
• Issue #21276: posixmodule: Don’t define USE_XATTRS on KFreeBSD and the Hurd.
• Issue #21262: New method assert_not_called for Mock. It raises AssertionError if the mock has been called.
• Issue #21238: New keyword argument unsafe to Mock. It raises AttributeError incase of an attribute startswith assert or assret.
• Issue #20896: ssl.get_server_certificate() now uses PROTOCOL_SSLv23, not PROTOCOL_SSLv3, for maximum compatibility.
• Issue #21239: patch.stopall() didn’t work deterministically when the same name was patched more than once.
• Issue #21203: Updated fileConfig and dictConfig to remove inconsistencies. Thanks to Jure Koren for the patch.
• Issue #21222: Passing name keyword argument to mock.create_autospec now works.
• Issue #21197: Add lib64 -> lib symlink in venvs on 64-bit non-OS X POSIX.
• Issue #17498: Some SMTP servers disconnect after certain errors, violating strict RFC conformance. Instead of losing the error code when we issue the subsequent RSET, smtplib now returns the error code and defers raising the SMTPServerDisconnected error until the next command is issued.
• Issue #17826: setting an iterable side_effect on a mock function created by create_autospec now works. Patch by Kushal Das.
• Issue #7776: Fix Host: header and reconnection when using http.client.HTTPConnection.set_tunnel(). Patch by Nikolaus Rath.
• Issue #20968: unittest.mock.MagicMock now supports division. Patch by Johannes Baiter.
• Fix arbitrary memory access in JSONDecoder.raw_decode with a negative second parameter. Bug reported by Guido Vranken.
• Issue #21169: getpass now handles non-ascii characters that the input stream encoding cannot encode by re-encoding using the replace error handler.
• Issue #21171: Fixed undocumented filter API of the rot13 codec. Patch by Berker Peksag.
• Issue #20539: Improved math.factorial error message for large positive inputs and changed exception type (OverflowError -> ValueError) for large negative inputs.
• Issue #21172: isinstance check relaxed from dict to collections.Mapping.
• Issue #21155: asyncio.EventLoop.create_unix_server() now raises a ValueError if path and sock are specified at the same time.
• Issue #21136: Avoid unnecessary normalization of Fractions resulting from power and other operations. Patch by Raymond Hettinger.
• Issue #17621: Introduce importlib.util.LazyLoader.
• Issue #21076: signal module constants were turned into enums. Patch by Giampaolo Rodola’.
• Issue #20636: Improved the repr of Tkinter widgets.
• Issue #19505: The items, keys, and values views of OrderedDict now support reverse iteration using reversed().
• Issue #21149: Improved thread-safety in logging cleanup during interpreter shutdown. Thanks to Devin Jeanpierre for the patch.
• Issue #21058: Fix a leak of file descriptor in tempfile.NamedTemporaryFile(), close the file descriptor if io.open() fails
• Issue #21200: Return None from pkgutil.get_loader() when __spec__ is missing.
• Issue #21013: Enhance ssl.create_default_context() when used for server side sockets to provide better security by default.
• Issue #20145: assertRaisesRegex and assertWarnsRegex now raise a TypeError if the second argument is not a string or compiled regex.
• Issue #20633: Replace relative import by absolute import.
• Issue #20980: Stop wrapping exception when using ThreadPool.
• Issue #21082: In os.makedirs, do not set the process-wide umask. Note this changes behavior of makedirs when exist_ok=True.
• Issue #20990: Fix issues found by pyflakes for multiprocessing.
• Issue #21015: SSL contexts will now automatically select an elliptic curve for ECDH key exchange on OpenSSL 1.0.2 and later, and otherwise default to “prime256v1”.
• Issue #21000: Improve the command-line interface of json.tool.
• Issue #20995: Enhance default ciphers used by the ssl module to enable better security an prioritize perfect forward secrecy.
• Issue #20884: Don’t assume that __file__ is defined on importlib.__init__.
• Issue #21499: Ignore __builtins__ in several test_importlib.test_api tests.
• Issue #20627: xmlrpc.client.ServerProxy is now a context manager.
• Issue #19165: The formatter module now raises DeprecationWarning instead of PendingDeprecationWarning.
• Issue #13936: Remove the ability of datetime.time instances to be considered false in boolean contexts.
• Issue #18931: selectors module now supports /dev/poll on Solaris. Patch by Giampaolo Rodola’.
• Issue #19977: When the LC_TYPE locale is the POSIX locale (C locale), sys.stdin and sys.stdout are now using the surrogateescape error handler, instead of the strict error handler.
• Issue #20574: Implement incremental decoder for cp65001 code (Windows code page 65001, Microsoft UTF-8).
• Issue #20879: Delay the initialization of encoding and decoding tables for base32, ascii85 and base85 codecs in the base64 module, and delay the initialization of the unquote_to_bytes() table of the urllib.parse module, to not waste memory if these modules are not used.
• Issue #19157: Include the broadcast address in the usuable hosts for IPv6 in ipaddress.
• Issue #11599: When an external command (e.g. compiler) fails, distutils now prints out the whole command line (instead of just the command name) if the environment variable DISTUTILS_DEBUG is set.
• Issue #4931: distutils should not produce unhelpful “error: None” messages anymore. distutils.util.grok_environment_error is kept but doc-deprecated.
• Issue #20875: Prevent possible gzip “‘read’ is not defined” NameError. Patch by Claudiu Popa.
• Issue #11558: email.message.Message.attach now returns a more useful error message if attach is called on a message for which is_multipart is False.
• Issue #20283: RE pattern methods now accept the string keyword parameters as documented. The pattern and source keyword parameters are left as deprecated aliases.
• Issue #20778: Fix modulefinder to work with bytecode-only modules.
• Issue #20791: copy.copy() now doesn’t make a copy when the input is a bytes object. Initial patch by Peter Otten.
• Issue #19748: On AIX, time.mktime() now raises an OverflowError for year outsize range [1902; 2037].
• Issue #19573: inspect.signature: Use enum for parameter kind constants.
• Issue #20726: inspect.signature: Make Signature and Parameter picklable.
• Issue #17373: Add inspect.Signature.from_callable method.
• Issue #20378: Improve repr of inspect.Signature and inspect.Parameter.
• Issue #20816: Fix inspect.getcallargs() to raise correct TypeError for missing keyword-only arguments. Patch by Jeremiah Lowin.
• Issue #20817: Fix inspect.getcallargs() to fail correctly if more than 3 arguments are missing. Patch by Jeremiah Lowin.
• Issue #6676: Ensure a meaningful exception is raised when attempting to parse more than one XML document per pyexpat xmlparser instance. (Original patches by Hirokazu Yamamoto and Amaury Forgeot d’Arc, with suggested wording by David Gutteridge)
• Issue #21117: Fix inspect.signature to better support functools.partial. Due to the specifics of functools.partial implementation, positional-or-keyword arguments passed as keyword arguments become keyword-only.
• Issue #20334: inspect.Signature and inspect.Parameter are now hashable. Thanks to Antony Lee for bug reports and suggestions.
• Issue #15916: doctest.DocTestSuite returns an empty unittest.TestSuite instead of raising ValueError if it finds no tests
• Issue #21209: Fix asyncio.tasks.CoroWrapper to workaround a bug in yield-from implementation in CPythons prior to 3.4.1.
• asyncio: Add gi_{frame,running,code} properties to CoroWrapper (upstream issue #163).
• Issue #21311: Avoid exception in _osx_support with non-standard compiler configurations. Patch by John Szakmeister.
• Issue #11571: Ensure that the turtle window becomes the topmost window when launched on OS X.
• Issue #21801: Validate that __signature__ is None or an instance of Signature.
• Issue #21923: Prevent AttributeError in distutils.sysconfig.customize_compiler due to possible uninitialized _config_vars.
• Issue #21323: Fix http.server to again handle scripts in CGI subdirectories, broken by the fix for security issue #19435. Patch by Zach Byrne.
• Issue #22733: Fix ffi_prep_args not zero-extending argument values correctly on 64-bit Windows.
• Issue #23302: Default to TCP_NODELAY=1 upon establishing an HTTPConnection. Removed use of hard-coded MSS as it’s an optimization that’s no longer needed with Nagle disabled.

IDLE

• Issue #20577: Configuration of the max line length for the FormatParagraph extension has been moved from the General tab of the Idle preferences dialog to the FormatParagraph tab of the Config Extensions dialog. Patch by Tal Einat.
• Issue #16893: Update Idle doc chapter to match current Idle and add new information.
• Issue #3068: Add Idle extension configuration dialog to Options menu. Changes are written to HOME/.idlerc/config-extensions.cfg. Original patch by Tal Einat.
• Issue #16233: A module browser (File : Class Browser, Alt+C) requires a editor window with a filename. When Class Browser is requested otherwise, from a shell, output window, or ‘Untitled’ editor, Idle no longer displays an error box. It now pops up an Open Module box (Alt+M). If a valid name is entered and a module is opened, a corresponding browser is also opened.
• Issue #4832: Save As to type Python files automatically adds .py to the name you enter (even if your system does not display it). Some systems automatically add .txt when type is Text files.
• Issue #21986: Code objects are not normally pickled by the pickle module. To match this, they are no longer pickled when running under Idle.
• Issue #17390: Adjust Editor window title; remove ‘Python’, move version to end.
• Issue #14105: Idle debugger breakpoints no longer disappear when inseting or deleting lines.
• Issue #17172: Turtledemo can now be run from Idle. Currently, the entry is on the Help menu, but it may move to Run. Patch by Ramchandra Apt and Lita Cho.
• Issue #21765: Add support for non-ascii identifiers to HyperParser.
• Issue #21940: Add unittest for WidgetRedirector. Initial patch by Saimadhav Heblikar.
• Issue #18592: Add unittest for SearchDialogBase. Patch by Phil Webster.
• Issue #21694: Add unittest for ParenMatch. Patch by Saimadhav Heblikar.
• Issue #21686: add unittest for HyperParser. Original patch by Saimadhav Heblikar.
• Issue #12387: Add missing upper(lower)case versions of default Windows key bindings for Idle so Caps Lock does not disable them. Patch by Roger Serwy.
• Issue #21695: Closing a Find-in-files output window while the search is still in progress no longer closes Idle.
• Issue #18910: Add unittest for textView. Patch by Phil Webster.
• Issue #18292: Add unittest for AutoExpand. Patch by Saihadhav Heblikar.
• Issue #18409: Add unittest for AutoComplete. Patch by Phil Webster.
• Issue #21477: htest.py - Improve framework, complete set of tests. Patches by Saimadhav Heblikar
• Issue #18104: Add idlelib/idle_test/htest.py with a few sample tests to begin consolidating and improving human-validated tests of Idle. Change other files as needed to work with htest. Running the module as __main__ runs all tests.
• Issue #21139: Change default paragraph width to 72, the PEP 8 recommendation.
• Issue #21284: Paragraph reformat test passes after user changes reformat width.
• Issue #17654: Ensure IDLE menus are customized properly on OS X for non-framework builds and for all variants of Tk.
• Issue #23180: Rename IDLE “Windows” menu item to “Window”. Patch by Al Sweigart.

Build

• Issue #15506: Use standard PKG_PROG_PKG_CONFIG autoconf macro in the configure script.
• Issue #22935: Allow the ssl module to be compiled if openssl doesn’t support SSL 3.
• Issue #22592: Drop support of the Borland C compiler to build Python. The distutils module still supports it to build extensions.
• Issue #22591: Drop support of MS-DOS, especially of the DJGPP compiler (MS-DOS port of GCC).
• Issue #16537: Check whether self.extensions is empty in setup.py. Patch by Jonathan Hosmer.
• Issue #22359: Remove incorrect uses of recursive make. Patch by Jonas Wagner.
• Issue #21958: Define HAVE_ROUND when building with Visual Studio 2013 and above. Patch by Zachary Turner.
• Issue #18093: the programs that embed the CPython runtime are now in a separate “Programs” directory, rather than being kept in the Modules directory.
• Issue #15759: “make suspicious”, “make linkcheck” and “make doctest” in Doc/ now display special message when and only when there are failures.
• Issue #21141: The Windows build process no longer attempts to find Perl, instead relying on OpenSSL source being configured and ready to build. The PCbuild\build_ssl.py script has been re-written and re-named to PCbuild\prepare_ssl.py, and takes care of configuring OpenSSL source for both 32 and 64 bit platforms. OpenSSL sources obtained from svn.python.org will always be pre-configured and ready to build.
• Issue #21037: Add a build option to enable AddressSanitizer support.
• Issue #19962: The Windows build process now creates “python.bat” in the root of the source tree, which passes all arguments through to the most recently built interpreter.
• Issue #21285: Refactor and fix curses configure check to always search in a ncursesw directory.
• Issue #15234: For BerkelyDB and Sqlite, only add the found library and include directories if they aren’t already being searched. This avoids an explicit runtime library dependency.
• Issue #17861: Tools/scripts/generate_opcode_h.py automatically regenerates Include/opcode.h from Lib/opcode.py if the later gets any change.
• Issue #20644: OS X installer build support for documentation build changes in 3.4.1: assume externally supplied sphinx-build is available in /usr/bin.
• Issue #20022: Eliminate use of deprecated bundlebuilder in OS X builds.
• Issue #15968: Incorporated Tcl, Tk, and Tix builds into the Windows build solution.
• Issue #17095: Fix Modules/Setup shared support.
• Issue #21811: Anticipated fixes to support OS X versions > 10.9.
• Issue #21166: Prevent possible segfaults and other random failures of python –generate-posix-vars in pybuilddir.txt build target.
• Issue #18096: Fix library order returned by python-config.
• Issue #17219: Add library build dir for Python extension cross-builds.
• Issue #22919: Windows build updated to support VC 14.0 (Visual Studio 2015), which will be used for the official release.
• Issue #21236: Build _msi.pyd with cabinet.lib instead of fci.lib
• Issue #17128: Use private version of OpenSSL for OS X 10.5+ installer.

C API

• Issue #14203: Remove obsolete support for view==NULL in PyBuffer_FillInfo(), bytearray_getbuffer(), bytesiobuf_getbuffer() and array_buffer_getbuf(). All functions now raise BufferError in that case.
• Issue #22445: PyBuffer_IsContiguous() now implements precise contiguity tests, compatible with NumPy’s NPY_RELAXED_STRIDES_CHECKING compilation flag. Previously the function reported false negatives for corner cases.
• Issue #22079: PyType_Ready() now checks that statically allocated type has no dynamically allocated bases.
• Issue #22453: Removed non-documented macro PyObject_REPR().
• Issue #18395: Rename _Py_char2wchar() to Py_DecodeLocale(), rename _Py_wchar2char() to Py_EncodeLocale(), and document these functions.
• Issue #21233: Add new C functions: PyMem_RawCalloc(), PyMem_Calloc(), PyObject_Calloc(), _PyObject_GC_Calloc(). bytes(int) is now using calloc() instead of malloc() for large objects which is faster and use less memory.
• Issue #20942: PyImport_ImportFrozenModuleObject() no longer sets __file__ to match what importlib does; this affects _frozen_importlib as well as any module loaded using imp.init_frozen().

Documentation

• Issue #19548: Update the codecs module documentation to better cover the distinction between text encodings and other codecs, together with other clarifications. Patch by Martin Panter.
• Issue #22394: Doc/Makefile now supports make venv PYTHON=../python to create a venv for generating the documentation, e.g., make html PYTHON=venv/bin/python3.
• Issue #21514: The documentation of the json module now refers to new JSON RFC 7159 instead of obsoleted RFC 4627.
• Issue #21777: The binary sequence methods on bytes and bytearray are now documented explicitly, rather than assuming users will be able to derive the expected behaviour from the behaviour of the corresponding str methods.
• Issue #6916: undocument deprecated asynchat.fifo class.
• Issue #17386: Expanded functionality of the Doc/make.bat script to make it much more comparable to Doc/Makefile.
• Issue #21312: Update the thread_foobar.h template file to include newer threading APIs. Patch by Jack McCracken.
• Issue #21043: Remove the recommendation for specific CA organizations and to mention the ability to load the OS certificates.
• Issue #20765: Add missing documentation for PurePath.with_name() and PurePath.with_suffix().
• Issue #19407: New package installation and distribution guides based on the Python Packaging Authority tools. Existing guides have been retained as legacy links from the distutils docs, as they still contain some required reference material for tool developers that isn’t recorded anywhere else.
• Issue #19697: Document cases where __main__.__spec__ is None.

Tests

• Issue #18982: Add tests for CLI of the calendar module.
• Issue #19548: Added some additional checks to test_codecs to ensure that statements in the updated documentation remain accurate. Patch by Martin Panter.
• Issue #22838: All test_re tests now work with unittest test discovery.
• Issue #22173: Update lib2to3 tests to use unittest test discovery.
• Issue #16000: Convert test_curses to use unittest.
• Issue #21456: Skip two tests in test_urllib2net.py if _ssl module not present. Patch by Remi Pointel.
• Issue #20746: Fix test_pdb to run in refleak mode (-R). Patch by Xavier de Gaye.
• Issue #22060: test_ctypes has been somewhat cleaned up and simplified; it now uses unittest test discovery to find its tests.
• Issue #22104: regrtest.py no longer holds a reference to the suite of tests loaded from test modules that don’t define test_main().
• Issue #22111: Assorted cleanups in test_imaplib. Patch by Milan Oberkirch.
• Issue #22002: Added load_package_tests function to test.support and used it to implement/augment test discovery in test_asyncio, test_email, test_importlib, test_json, and test_tools.
• Issue #21976: Fix test_ssl to accept LibreSSL version strings. Thanks to William Orr.
• Issue #21918: Converted test_tools from a module to a package containing separate test files for each tested script.
• Issue #9554: Use modern unittest features in test_argparse. Initial patch by Denver Coneybeare and Radu Voicilas.
• Issue #20155: Changed HTTP method names in failing tests in test_httpservers so that packet filtering software (specifically Windows Base Filtering Engine) does not interfere with the transaction semantics expected by the tests.
• Issue #19493: Refactored the ctypes test package to skip tests explicitly rather than silently.
• Issue #18492: All resources are now allowed when tests are not run by regrtest.py.
• Issue #21634: Fix pystone micro-benchmark: use floor division instead of true division to benchmark integers instead of floating point numbers. Set pystone version to 1.2. Patch written by Lennart Regebro.
• Issue #21605: Added tests for Tkinter images.
• Issue #21493: Added test for ntpath.expanduser(). Original patch by Claudiu Popa.
• Issue #19925: Added tests for the spwd module. Original patch by Vajrasky Kok.
• Issue #21522: Added Tkinter tests for Listbox.itemconfigure(), PanedWindow.paneconfigure(), and Menu.entryconfigure().
• Issue #17756: Fix test_code test when run from the installed location.
• Issue #17752: Fix distutils tests when run from the installed location.
• Issue #18604: Consolidated checks for GUI availability. All platforms now at least check whether Tk can be instantiated when the GUI resource is requested.
• Issue #21275: Fix a socket test on KFreeBSD.
• Issue #21223: Pass test_site/test_startup_imports when some of the extensions are built as builtins.
• Issue #20635: Added tests for Tk geometry managers.
• Add test case for freeze.
• Issue #20743: Fix a reference leak in test_tcl.
• Issue #21097: Move test_namespace_pkgs into test_importlib.
• Issue #21503: Use test_both() consistently in test_importlib.
• Issue #20939: Avoid various network test failures due to new redirect of http://www.python.org/ to https://www.python.org: use http://www.example.com instead.
• Issue #20668: asyncio tests no longer rely on tests.txt file. (Patch by Vajrasky Kok)
• Issue #21093: Prevent failures of ctypes test_macholib on OS X if a copy of libz exists in $HOME/lib or /usr/local/lib.
• Issue #22770: Prevent some Tk segfaults on OS X when running gui tests.
• Issue #23211: Workaround test_logging failure on some OS X 10.6 systems.
• Issue #23345: Prevent test_ssl failures with large OpenSSL patch level values (like 0.9.8zc).

Tools/Demos

• Issue #22314: pydoc now works when the LINES environment variable is set.
• Issue #22615: Argument Clinic now supports the “type” argument for the int converter. This permits using the int converter with enums and typedefs.
• Issue #20076: The makelocalealias.py script no longer ignores UTF-8 mapping.
• Issue #20079: The makelocalealias.py script now can parse the SUPPORTED file from glibc sources and supports command line options for source paths.
• Issue #22201: Command-line interface of the zipfile module now correctly extracts ZIP files with directory entries. Patch by Ryan Wilson.
• Issue #22120: For functions using an unsigned integer return converter, Argument Clinic now generates a cast to that type for the comparison to -1 in the generated code. (This supresses a compilation warning.)
• Issue #18974: Tools/scripts/diff.py now uses argparse instead of optparse.
• Issue #21906: Make Tools/scripts/md5sum.py work in Python 3. Patch by Zachary Ware.
• Issue #21629: Fix Argument Clinic’s “–converters” feature.
• Add support for yield from to 2to3.
• Add support for the PEP 465 matrix multiplication operator to 2to3.
• Issue #16047: Fix module exception list and __file__ handling in freeze. Patch by Meador Inge.
• Issue #11824: Consider ABI tags in freeze. Patch by Meador Inge.
• Issue #20535: PYTHONWARNING no longer affects the run_tests.py script. Patch by Arfrever Frehtes Taifersar Arahesis.

Windows

• Issue #23260: Update Windows installer
• The bundled version of Tcl/Tk has been updated to 8.6.3. The most visible result of this change is the addition of new native file dialogs when running on Windows Vista or newer. See Tcl/Tk’s TIP 432 for more information. Also, this version of Tcl/Tk includes support for Windows 10.
• Issue #17896: The Windows build scripts now expect external library sources to be in PCbuild\..\externals rather than PCbuild\..\...
• Issue #17717: The Windows build scripts now use a copy of NASM pulled from svn.python.org to build OpenSSL.
• Issue #21907: Improved the batch scripts provided for building Python.
• Issue #22644: The bundled version of OpenSSL has been updated to 1.0.1j.
• Issue #10747: Use versioned labels in the Windows start menu. Patch by Olive Kilburn.
• Issue #22980: .pyd files with a version and platform tag (for example, ”.cp35-win32.pyd”) will now be loaded in preference to those without tags.

Library

• Issue #20939: Fix test_geturl failure in test_urllibnet due to new redirect of http://www.python.org/ to https://www.python.org.

Documentation

• Merge in all documentation changes since branching 3.4.0rc1.

Core and Builtins

• Issue #20786: Fix signatures for dict.__delitem__ and property.__delete__ builtins.

Library

• Issue #20839: Don’t trigger a DeprecationWarning in the still supported pkgutil.get_loader() API when __loader__ isn’t set on a module (nor when pkgutil.find_loader() is called directly).

Build

• Issue #14512: Launch pydoc -b instead of pydocgui.pyw on Windows.
• Issue #20748: Uninstalling pip does not leave behind the pyc of the uninstaller anymore.
• Issue #20568: The Windows installer now installs the unversioned pip command in addition to the versioned pip3 and pip3.4 commands.
• Issue #20757: The ensurepip helper for the Windows uninstaller now skips uninstalling pip (rather than failing) if the user has updated pip to a different version from the one bundled with ensurepip.
• Issue #20465: Update OS X and Windows installer builds to use SQLite 3.8.3.1.

Core and Builtins

• Issue #20625: Parameter names in __annotations__ were not mangled properly. Discovered by Jonas Wielicki, patch by Yury Selivanov.
• Issue #20261: In pickle, lookup __getnewargs__ and __getnewargs_ex__ on the type of the object.
• Issue #20619: Give the AST nodes of keyword-only arguments a column and line number.
• Issue #20526: Revert changes of issue #19466 which introduces a regression: don’t clear anymore the state of Python threads early during the Python shutdown.

Library

• Issue #20710: The pydoc summary line no longer displays the “self” parameter for bound methods.
• Issue #20566: Change asyncio.as_completed() to use a Queue, to avoid O(N**2) behavior.
• Issue #20704: Implement new debug API in asyncio. Add new methods BaseEventLoop.set_debug() and BaseEventLoop.get_debug(). Add support for setting ‘asyncio.tasks._DEBUG’ variable with ‘PYTHONASYNCIODEBUG’ environment variable.
• asyncio: Refactoring and fixes: BaseEventLoop.sock_connect() raises an error if the address is not resolved; use __slots__ in Handle and TimerHandle; as_completed() and wait() raise TypeError if the passed list of Futures is a single Future; call_soon() and other ‘call_*()’ functions raise TypeError if the passed callback is a coroutine function; _ProactorBasePipeTransport uses _FlowControlMixin; WriteTransport.set_write_buffer_size() calls _maybe_pause_protocol() to consider pausing receiving if the watermark limits have changed; fix _check_resolved_address() for IPv6 address; and other minor improvements, along with multiple documentation updates.
• Issue #20684: Fix inspect.getfullargspec() to not to follow __wrapped__ chains. Make its behaviour consistent with bound methods first argument. Patch by Nick Coghlan and Yury Selivanov.
• Issue #20681: Add new error handling API in asyncio. New APIs: loop.set_exception_handler(), loop.default_exception_handler(), and loop.call_exception_handler().
• Issue #20673: Implement support for UNIX Domain Sockets in asyncio. New APIs: loop.create_unix_connection(), loop.create_unix_server(), streams.open_unix_connection(), and streams.start_unix_server().
• Issue #20616: Add a format() method to tracemalloc.Traceback.
• Issue #19744: the ensurepip installation step now just prints a warning to stderr rather than failing outright if SSL/TLS is unavailable. This allows local installation of POSIX builds without SSL/TLS support.
• Issue #20594: Avoid name clash with the libc function posix_close.

Build

• Issue #20641: Run MSI custom actions (pip installation, pyc compilation) with the NoImpersonate flag, to support elevated execution (UAC).
• Issue #20221: Removed conflicting (or circular) hypot definition when compiled with VS 2010 or above. Initial patch by Tabrez Mohammed.
• Issue #20609: Restored the ability to build 64-bit Windows binaries on 32-bit Windows, which was broken by the change in issue #19788.

Core and Builtins

• Issue #19255: The builtins module is restored to initial value before cleaning other modules. The sys and builtins modules are cleaned last.
• Issue #20588: Make Python-ast.c C89 compliant.
• Issue #20437: Fixed 22 potential bugs when deleting objects references.
• Issue #20500: Displaying an exception at interpreter shutdown no longer risks triggering an assertion failure in PyObject_Str.
• Issue #20538: UTF-7 incremental decoder produced inconsistent string when input was truncated in BASE64 section.
• Issue #20404: io.TextIOWrapper (and hence the open() builtin) now uses the internal codec marking system added for issue #19619 to throw LookupError for known non-text encodings at stream construction time. The existing output type checks remain in place to deal with unmarked third party codecs.
• Issue #17162: Add PyType_GetSlot.
• Issue #20162: Fix an alignment issue in the siphash24() hash function which caused a crash on PowerPC 64-bit (ppc64).

Library

• Issue #20530: The signatures for slot builtins have been updated to reflect the fact that they only accept positional-only arguments.
• Issue #20517: Functions in the os module that accept two filenames now register both filenames in the exception on failure.
• Issue #20563: The ipaddress module API is now considered stable.
• Issue #14983: email.generator now always adds a line end after each MIME boundary marker, instead of doing so only when there is an epilogue. This fixes an RFC compliance bug and solves an issue with signed MIME parts.
• Issue #20540: Fix a performance regression (vs. Python 3.2) when layering a multiprocessing Connection over a TCP socket. For small payloads, Nagle’s algorithm would introduce idle delays before the entire transmission of a message.
• Issue #16983: the new email header parsing code will now decode encoded words that are (incorrectly) surrounded by quotes, and register a defect.
• Issue #19772: email.generator no longer mutates the message object when doing a down-transform from 8bit to 7bit CTEs.
• Issue #20536: the statistics module now correctly handle Decimal instances with positive exponents
• Issue #18805: the netmask/hostmask parsing in ipaddress now more reliably filters out illegal values and correctly allows any valid prefix length.
• Issue #20481: For at least Python 3.4, the statistics module will require that all inputs for a single operation be of a single consistent type, or else a mixed of ints and a single other consistent type. This avoids some interoperability issues that arose with the previous approach of coercing to a suitable common type.
• Issue #20478: the statistics module now treats collections.Counter inputs like any other iterable.
• Issue #17369: get_filename was raising an exception if the filename parameter’s RFC2231 encoding was broken in certain ways. This was a regression relative to python2.
• Issue #20013: Some imap servers disconnect if the current mailbox is deleted, and imaplib did not handle that case gracefully. Now it handles the ‘bye’ correctly.
• Issue #20531: Revert 3.4 version of fix for #19063, and apply the 3.3 version. That is, do not raise an error if unicode is passed to email.message.Message.set_payload.
• Issue #20476: If a non-compat32 policy is used with any of the email parsers, EmailMessage is now used as the factory class. The factory class should really come from the policy; that will get fixed in 3.5.
• Issue #19920: TarFile.list() no longer fails when outputs a listing containing non-encodable characters. Based on patch by Vajrasky Kok.
• Issue #20515: Fix NULL pointer dereference introduced by issue #20368.
• Issue #19186: Restore namespacing of expat symbols inside the pyexpat module.
• Issue #20053: ensurepip (and hence venv) are no longer affected by the settings in the default pip configuration file.
• Issue #20426: When passing the re.DEBUG flag, re.compile() displays the debug output every time it is called, regardless of the compilation cache.
• Issue #20368: The null character now correctly passed from Tcl to Python. Improved error handling in variables-related commands.
• Issue #20435: Fix _pyio.StringIO.getvalue() to take into account newline translation settings.
• tracemalloc: Fix slicing traces and fix slicing a traceback.
• Issue #20354: Fix an alignment issue in the tracemalloc module on 64-bit platforms. Bug seen on 64-bit Linux when using “make profile-opt”.
• Issue #17159: inspect.signature now accepts duck types of functions, which adds support for Cython functions. Initial patch by Stefan Behnel.
• Issue #18801: Fix inspect.classify_class_attrs to correctly classify object.__new__ and object.__init__.
• Fixed cmath.isinf’s name in its argument parsing code.
• Issue #20311, #20452: poll and epoll now round the timeout away from zero, instead of rounding towards zero, in select and selectors modules: select.epoll.poll(), selectors.PollSelector.poll() and selectors.EpollSelector.poll(). For example, a timeout of one microsecond (1e-6) is now rounded to one millisecondi (1e-3), instead of being rounded to zero. However, the granularity property and asyncio’s resolution feature were removed again.
• asyncio: Some refactoring; various fixes; add write flow control to unix pipes; Future.set_exception() instantiates the exception argument if it is a class; improved proactor pipe transport; support wait_for(f, None); don’t log broken/disconnected pipes; use ValueError instead of assert for forbidden subprocess_{shell,exec} arguments; added a convenience API for subprocess management; added StreamReader.at_eof(); properly handle duplicate coroutines/futures in gather(), wait(), as_completed(); use a bytearray for buffering in StreamReader; and more.
• Issue #20288: fix handling of invalid numeric charrefs in HTMLParser.
• Issue #20424: Python implementation of io.StringIO now supports lone surrogates.
• Issue #20308: inspect.signature now works on classes without user-defined __init__ or __new__ methods.
• Issue #20372: inspect.getfile (and a bunch of other inspect functions that use it) doesn’t crash with unexpected AttributeError on classes defined in C without __module__.
• Issue #20356: inspect.signature formatting uses ‘/’ to separate positional-only parameters from others.
• Issue #20223: inspect.signature now supports methods defined with functools.partialmethods.
• Issue #19456: ntpath.join() now joins relative paths correctly when a drive is present.
• Issue #19077: tempfile.TemporaryDirectory cleanup no longer fails when called during shutdown. Emitting resource warning in __del__ no longer fails. Original patch by Antoine Pitrou.
• Issue #20394: Silence Coverity warning in audioop module.
• Issue #20367: Fix behavior of concurrent.futures.as_completed() for duplicate arguments. Patch by Glenn Langford.
• Issue #8260: The read(), readline() and readlines() methods of codecs.StreamReader returned incomplete data when were called after readline() or read(size). Based on patch by Amaury Forgeot d’Arc.
• Issue #20105: the codec exception chaining now correctly sets the traceback of the original exception as its __traceback__ attribute.
• Issue #17481: inspect.getfullargspec() now uses inspect.signature() API.
• Issue #15304: concurrent.futures.wait() can block forever even if Futures have completed. Patch by Glenn Langford.
• Issue #14455: plistlib: fix serializing integers in the range of an unsigned long long but outside of the range of signed long long for binary plist files.

IDLE

• Issue #20406: Use Python application icons for Idle window title bars. Patch mostly by Serhiy Storchaka.
• Update the python.gif icon for the Idle classbrowser and pathbowser from the old green snake to the new blue and yellow snakes.
• Issue #17721: Remove non-functional configuration dialog help button until we make it actually gives some help when clicked. Patch by Guilherme Simões.

Tests

• Issue #20532: Tests which use _testcapi now are marked as CPython only.
• Issue #19920: Added tests for TarFile.list(). Based on patch by Vajrasky Kok.
• Issue #19990: Added tests for the imghdr module. Based on patch by Claudiu Popa.
• Issue #20474: Fix test_socket “unexpected success” failures on OS X 10.7+.

Tools/Demos

• Issue #20530: Argument Clinic’s signature format has been revised again. The new syntax is highly human readable while still preventing false positives. The syntax also extends Python syntax to denote “self” and positional-only parameters, allowing inspect.Signature objects to be totally accurate for all supported builtins in Python 3.4.
• Issue #20456: Argument Clinic now observes the C preprocessor conditional compilation statements of the C files it parses. When a Clinic block is inside a conditional code, it adjusts its output to match, including automatically generating an empty methoddef macro.
• Issue #20456: Cloned functions in Argument Clinic now use the correct name, not the name of the function they were cloned from, for text strings inside generated code.
• Issue #20456: Fixed Argument Clinic’s test suite and “–converters” feature.
• Issue #20456: Argument Clinic now allows specifying different names for a parameter in Python and C, using “as” on the parameter line.
• Issue #20326: Argument Clinic now uses a simple, unique signature to annotate text signatures in docstrings, resulting in fewer false positives. “self” parameters are also explicitly marked, allowing inspect.Signature() to authoritatively detect (and skip) said parameters.
• Issue #20326: Argument Clinic now generates separate checksums for the input and output sections of the block, allowing external tools to verify that the input has not changed (and thus the output is not out-of-date).

Build

• Issue #20465: Update SQLite shipped with OS X installer to 3.8.3.

C-API

• Issue #20517: Added new functions allowing OSError exceptions to reference two filenames instead of one: PyErr_SetFromErrnoWithFilenameObjects() and PyErr_SetExcFromWindowsErrWithFilenameObjects().

Documentation

• Issue #20488: Change wording to say importlib is the implementation of import instead of just an implementation.
• Issue #6386: Clarify in the tutorial that specifying a symlink to execute means the directory containing the executed script and not the symlink is added to sys.path.

Core and Builtins

• Issue #20189: Four additional builtin types (PyTypeObject, PyMethodDescr_Type, _PyMethodWrapper_Type, and PyWrapperDescr_Type) have been modified to provide introspection information for builtins.
• Issue #17825: Cursor “^” is correctly positioned for SyntaxError and IndentationError.
• Issue #2382: SyntaxError cursor “^” is now written at correct position in most cases when multibyte characters are in line (before “^”). This still not works correctly with wide East Asian characters.
• Issue #18960: The first line of Python script could be executed twice when the source encoding was specified on the second line. Now the source encoding declaration on the second line isn’t effective if the first line contains anything except a comment. ‘python -x’ works now again with files with the source encoding declarations, and can be used to make Python batch files on Windows.

Library

• asyncio: Various improvements and small changes not all covered by issues listed below. E.g. wait_for() now cancels the inner task if the timeout occcurs; tweaked the set of exported symbols; renamed Empty/Full to QueueEmpty/QueueFull; “with (yield from lock)” now uses a separate context manager; readexactly() raises if not enough data was read; PTY support tweaks.
• Issue #20311: asyncio: Add a granularity attribute to BaseEventLoop: maximum between the resolution of the BaseEventLoop.time() method and the resolution of the selector. The granuarility is used in the scheduler to round time and deadline.
• Issue #20311: selectors: Add a resolution attribute to BaseSelector.
• Issue #20189: unittest.mock now no longer assumes that any object for which it could get an inspect.Signature is a callable written in Python. Fix courtesy of Michael Foord.
• Issue #20317: ExitStack.__exit__ could create a self-referential loop if an exception raised by a cleanup operation already had its context set correctly (for example, by the @contextmanager decorator). The infinite loop this caused is now avoided by checking if the expected context is already set before trying to fix it.
• Issue #20374: Fix build with GNU readline >= 6.3.
• Issue #20262: Warnings are raised now when duplicate names are added in the ZIP file or too long ZIP file comment is truncated.
• Issue #20165: The unittest module no longer considers tests marked with @expectedFailure successful if they pass.
• Issue #18574: Added missing newline in 100-Continue reply from http.server.BaseHTTPRequestHandler. Patch by Nikolaus Rath.
• Issue #20270: urllib.urlparse now supports empty ports.
• Issue #20243: TarFile no longer raise ReadError when opened in write mode.
• Issue #20238: TarFile opened with external fileobj and “w:gz” mode didn’t write complete output on close.
• Issue #20245: The open functions in the tarfile module now correctly handle empty mode.
• Issue #20242: Fixed basicConfig() format strings for the alternative formatting styles. Thanks to kespindler for the bug report and patch.
• Issue #20246: Fix buffer overflow in socket.recvfrom_into.
• Issues #20206 and #5803: Fix edge case in email.quoprimime.encode where it truncated lines ending in a character needing encoding but no newline by using a more efficient algorithm that doesn’t have the bug.
• Issue #19082: Working xmlrpc.server and xmlrpc.client examples. Both in modules and in documentation. Initial patch contributed by Vajrasky Kok.
• Issue #20138: The wsgiref.application_uri() and wsgiref.request_uri() functions now conform to PEP 3333 when handle non-ASCII URLs.
• Issue #19097: Raise the correct Exception when cgi.FieldStorage is given an invalid fileobj.
• Issue #20152: Ported Python/import.c over to Argument Clinic.
• Issue #13107: argparse and optparse no longer raises an exception when output a help on environment with too small COLUMNS. Based on patch by Elazar Gershuni.
• Issue #20207: Always disable SSLv2 except when PROTOCOL_SSLv2 is explicitly asked for.
• Issue #18960: The tokenize module now ignore the source encoding declaration on the second line if the first line contains anything except a comment.
• Issue #20078: Reading malformed zipfiles no longer hangs with 100% CPU consumption.
• Issue #20113: os.readv() and os.writev() now raise an OSError exception on error instead of returning -1.
• Issue #19719: Make importlib.abc.MetaPathFinder.find_module(), PathEntryFinder.find_loader(), and Loader.load_module() use PEP 451 APIs to help with backwards-compatibility.
• Issue #20144: inspect.Signature now supports parsing simple symbolic constants as parameter default values in __text_signature__.
• Issue #20072: Fixed multiple errors in tkinter with wantobjects is False.
• Issue #20229: Avoid plistlib deprecation warning in platform.mac_ver().
• Issue #14455: Fix some problems with the new binary plist support in plistlib.

IDLE

• Issue #17390: Add Python version to Idle editor window title bar. Original patches by Edmond Burnett and Kent Johnson.
• Issue #18960: IDLE now ignores the source encoding declaration on the second line if the first line contains anything except a comment.

Tests

• Issue #20358: Tests for curses.window.overlay and curses.window.overwrite no longer specify min{row,col} > max{row,col}.
• Issue #19804: The test_find_mac test in test_uuid is now skipped if the ifconfig executable is not available.
• Issue #19886: Use better estimated memory requirements for bigmem tests.

Tools/Demos

• Issue #20390: Argument Clinic’s “file” output preset now defaults to “{dirname}/clinic/{basename}.h”.
• Issue #20390: Argument Clinic’s “class” directive syntax has been extended with two new required arguments: “typedef” and “type_object”.
• Issue #20390: Argument Clinic: If __new__ or __init__ functions didn’t use kwargs (or args), the PyArg_NoKeywords (or PyArg_NoPositional) calls generated are only run when the type object is an exact match.
• Issue #20390: Argument Clinic now fails if you have required parameters after optional parameters.
• Issue #20390: Argument Clinic converters now have a new template they can inject code into: “modifiers”. Code put there is run in the parsing function after argument parsing but before the call to the impl.
• Issue #20376: Argument Clinic now escapes backslashes in docstrings.
• Issue #20381: Argument Clinic now sanity checks the default argument when c_default is also specified, providing a nice failure message for disallowed values.
• Issue #20189: Argument Clinic now ensures that parser functions for __new__ are always of type newfunc, the type of the tp_new slot. Similarly, parser functions for __init__ are now always of type initproc, the type of tp_init.
• Issue #20189: Argument Clinic now suppresses the docstring for __new__ and __init__ functions if no docstring is provided in the input.
• Issue #20189: Argument Clinic now suppresses the “self” parameter in the impl for @staticmethod functions.
• Issue #20294: Argument Clinic now supports argument parsing for __new__ and __init__ functions.
• Issue #20299: Argument Clinic custom converters may now change the default value of c_default and py_default with a class member.
• Issue #20287: Argument Clinic’s output is now configurable, allowing delaying its output or even redirecting it to a separate file.
• Issue #20226: Argument Clinic now permits simple expressions (e.g. “sys.maxsize - 1”) as default values for parameters.
• Issue #19936: Added executable bits or shebang lines to Python scripts which requires them. Disable executable bits and shebang lines in test and benchmark files in order to prevent using a random system python, and in source files of modules which don’t provide command line interface. Fixed shebang lines in the unittestgui and checkpip scripts.
• Issue #20268: Argument Clinic now supports cloning the parameters and return converter of existing functions.
• Issue #20228: Argument Clinic now has special support for class special methods.
• Issue #20214: Fixed a number of small issues and documentation errors in Argument Clinic (see issue for details).
• Issue #20196: Fixed a bug where Argument Clinic did not generate correct parsing code for functions with positional-only parameters where all arguments are optional.
• Issue #18960: 2to3 and the findnocoding.py script now ignore the source encoding declaration on the second line if the first line contains anything except a comment.
• Issue #19723: The marker comments Argument Clinic uses have been changed to improve readability.
• Issue #20157: When Argument Clinic renames a parameter because its name collides with a C keyword, it no longer exposes that rename to PyArg_Parse.
• Issue #20141: Improved Argument Clinic’s support for the PyArg_Parse “O!” format unit.
• Issue #20144: Argument Clinic now supports simple symbolic constants as parameter default values.
• Issue #20143: The line numbers reported in Argument Clinic errors are now more accurate.
• Issue #20142: Py_buffer variables generated by Argument Clinic are now initialized with a default value.

Build

• Issue #12837: Silence a tautological comparison warning on OS X under Clang in socketmodule.c.

Core and Builtins

• Issue #17432: Drop UCS2 from names of Unicode functions in python3.def.
• Issue #19526: Exclude all new API from the stable ABI. Exceptions can be made if a need is demonstrated.
• Issue #19969: PyBytes_FromFormatV() now raises an OverflowError if “%c” argument is not in range [0; 255].
• Issue #19995: %c, %o, %x, and %X now issue a DeprecationWarning on non-integer input; reworded docs to clarify that an integer type should define both __int__ and __index__.
• Issue #19787: PyThread_set_key_value() now always set the value. In Python 3.3, the function did nothing if the key already exists (if the current value is a non-NULL pointer).
• Issue #14432: Remove the thread state field from the frame structure. Fix a crash when a generator is created in a C thread that is destroyed while the generator is still used. The issue was that a generator contains a frame, and the frame kept a reference to the Python state of the destroyed C thread. The crash occurs when a trace function is setup.
• Issue #19576: PyGILState_Ensure() now initializes threads. At startup, Python has no concrete GIL. If PyGILState_Ensure() is called from a new thread for the first time and PyEval_InitThreads() was not called yet, a GIL needs to be created.
• Issue #17576: Deprecation warning emitted now when __int__() or __index__() return not int instance.
• Issue #19932: Fix typo in import.h, missing whitespaces in function prototypes.
• Issue #19736: Add module-level statvfs constants defined for GNU/glibc based systems.
• Issue #20097: Fix bad use of “self” in importlib’s WindowsRegistryFinder.
• Issue #19729: In str.format(), fix recursive expansion in format spec.
• Issue #19638: Fix possible crash / undefined behaviour from huge (more than 2 billion characters) input strings in _Py_dg_strtod.

Library

• Issue #20154: Deadlock in asyncio.StreamReader.readexactly().
• Issue #16113: Remove sha3 module again.
• Issue #20111: pathlib.Path.with_suffix() now sanity checks the given suffix.
• Fix breakage in TestSuite.countTestCases() introduced by issue #11798.
• Issue #20108: Avoid parameter name clash in inspect.getcallargs().
• Issue #19918: Fix PurePath.relative_to() under Windows.
• Issue #19422: Explicitly disallow non-SOCK_STREAM sockets in the ssl module, rather than silently let them emit clear text data.
• Issue #20046: Locale alias table no longer contains entities which can be calculated. Generalized support of the euro modifier.
• Issue #20027: Fixed locale aliases for devanagari locales.
• Issue #20067: Tkinter variables now work when wantobjects is false.
• Issue #19020: Tkinter now uses splitlist() instead of split() in configure methods.
• Issue #19744: ensurepip now provides a better error message when Python is built without SSL/TLS support (pip currently requires that support to run, even if only operating with local wheel files)
• Issue #19734: ensurepip now ignores all pip environment variables to avoid odd behaviour based on user configuration settings
• Fix TypeError on “setup.py upload –show-response”.
• Issue #20045: Fix “setup.py register –list-classifiers”.
• Issue #18879: When a method is looked up on a temporary file, avoid closing the file before the method is possibly called.
• Issue #20037: Avoid crashes when opening a text file late at interpreter shutdown.
• Issue #19967: Thanks to the PEP 442, asyncio.Future now uses a destructor to log uncaught exceptions, instead of the dedicated _TracebackLogger class.
• Added a Task.current_task() class method to asyncio.
• Issue #19850: Set SA_RESTART in asyncio when registering a signal handler to limit EINTR occurrences.
• Implemented write flow control in asyncio for proactor event loop (Windows).
• Change write buffer in asyncio use to avoid O(N**2) behavior. Make write()/sendto() accept bytearray/memoryview.
• Issue #20034: Updated alias mapping to most recent locale.alias file from X.org distribution using makelocalealias.py.
• Issue #5815: Fixed support for locales with modifiers. Fixed support for locale encodings with hyphens.
• Issue #20026: Fix the sqlite module to handle correctly invalid isolation level (wrong type).
• Issue #18829: csv.Dialect() now checks type for delimiter, escapechar and quotechar fields. Original patch by Vajrasky Kok.
• Issue #19855: uuid.getnode() on Unix now looks on the PATH for the executables used to find the mac address, with /sbin and /usr/sbin as fallbacks.
• Issue #20007: HTTPResponse.read(0) no more prematurely closes connection. Original patch by Simon Sapin.
• Issue #19946: multiprocessing now uses runpy to initialize __main__ in child processes when necessary, allowing it to correctly handle scripts without suffixes and submodules that use explicit relative imports or otherwise rely on parent modules being correctly imported prior to execution.
• Issue #19921: When Path.mkdir() is called with parents=True, any missing parent is created with the default permissions, ignoring the mode argument (mimicking the POSIX “mkdir -p” command).
• Issue #19887: Improve the Path.resolve() algorithm to support certain symlink chains.
• Issue #19912: Fixed numerous bugs in ntpath.splitunc().
• Issue #19911: ntpath.splitdrive() now correctly processes the ‘İ’ character (U+0130, LATIN CAPITAL LETTER I WITH DOT ABOVE).
• Issue #19532: python -m compileall with no filename/directory arguments now respects the -f and -q flags instead of ignoring them.
• Issue #19623: Fixed writing to unseekable files in the aifc module.
• Issue #19946: multiprocessing.spawn now raises ImportError when the module to be used as the main module cannot be imported.
• Issue #17919: select.poll.register() again works with poll.POLLNVAL on AIX. Fixed integer overflow in the eventmask parameter.
• Issue #19063: if a Charset’s body_encoding was set to None, the email package would generate a message claiming the Content-Transfer-Encoding was 7bit, and produce garbage output for the content. This now works. A couple of other set_payload mishandlings of non-ASCII are also fixed. In addition, calling set_payload with a string argument without specifying a charset now raises an error (this is a new error in 3.4).
• Issue #15475: Add __sizeof__ implementations for itertools objects.
• Issue #19944: Fix importlib.find_spec() so it imports parents as needed and move the function to importlib.util.
• Issue #19880: Fix a reference leak in unittest.TestCase. Explicitly break reference cycles between frames and the _Outcome instance.
• Issue #17429: platform.linux_distribution() now decodes files from the UTF-8 encoding with the surrogateescape error handler, instead of decoding from the locale encoding in strict mode. It fixes the function on Fedora 19 which is probably the first major distribution release with a non-ASCII name. Patch written by Toshio Kuratomi.
• Issue #19343: Expose FreeBSD-specific APIs in resource module. Original patch by Koobs.
• Issue #19929: Call os.read with 32768 within subprocess.Popen.communicate rather than 4096 for efficiency. A microbenchmark shows Linux and OS X both using ~50% less cpu time this way.
• Issue #19506: Use a memoryview to avoid a data copy when piping data to stdin within subprocess.Popen.communicate. 5-10% less cpu usage.
• Issue #19876: selectors unregister() no longer raises ValueError or OSError if the FD is closed (as long as it was registered).
• Issue #19908: pathlib now joins relative Windows paths correctly when a drive is present. Original patch by Antoine Pitrou.
• Issue #19296: Silence compiler warning in dbm_open
• Issue #6784: Strings from Python 2 can now be unpickled as bytes objects by setting the encoding argument of Unpickler to be ‘bytes’. Initial patch by Merlijn van Deen.
• Issue #19839: Fix regression in bz2 module’s handling of non-bzip2 data at EOF, and analogous bug in lzma module.
• Issue #19881: Fix pickling bug where cpickle would emit bad pickle data for large bytes string (i.e., with size greater than 2**32-1).
• Issue #19138: doctest’s IGNORE_EXCEPTION_DETAIL now allows a match when no exception detail exists (no colon following the exception’s name, or a colon does follow but no text follows the colon).
• Issue #19927: Add __eq__ to path-based loaders in importlib.
• Issue #19827: On UNIX, setblocking() and settimeout() methods of socket.socket can now avoid a second syscall if the ioctl() function can be used, or if the non-blocking flag of the socket is unchanged.
• Issue #19785: smtplib now supports SSLContext.check_hostname and server name indication for TLS/SSL connections.
• Issue #19784: poplib now supports SSLContext.check_hostname and server name indication for TLS/SSL connections.
• Issue #19783: nntplib now supports SSLContext.check_hostname and server name indication for TLS/SSL connections.
• Issue #19782: imaplib now supports SSLContext.check_hostname and server name indication for TLS/SSL connections.
• Issue #20123: Fix pydoc.synopsis() for “binary” modules.
• Issue #19834: Support unpickling of exceptions pickled by Python 2.
• Issue #19781: ftplib now supports SSLContext.check_hostname and server name indication for TLS/SSL connections.
• Issue #19509: Add SSLContext.check_hostname to match the peer’s certificate with server_hostname on handshake.
• Issue #15798: Fixed subprocess.Popen() to no longer fail if file descriptor 0, 1 or 2 is closed.
• Issue #17897: Optimized unpickle prefetching.
• Issue #3693: Make the error message more helpful when the array.array() constructor is given a str. Move the array module typecode documentation to the docstring of the constructor.
• Issue #19088: Fixed incorrect caching of the copyreg module in object.__reduce__() and object.__reduce_ex__().
• Issue #19698: Removed exec_module() methods from importlib.machinery.BuiltinImporter and ExtensionFileLoader.
• Issue #18864: Added a setter for ModuleSpec.has_location.
• Fixed _pickle.Unpickler to not fail when loading empty strings as persistent IDs.
• Issue #11480: Fixed copy.copy to work with classes with custom metaclasses. Patch by Daniel Urban.
• Issue #6477: Added support for pickling the types of built-in singletons (i.e., Ellipsis, NotImplemented, None).
• Issue #19713: Add remaining PEP 451-related deprecations and move away from using find_module/find_loaer/load_module.
• Issue #19708: Update pkgutil to use the new importer APIs.
• Issue #19703: Update pydoc to use the new importer APIs.
• Issue #19851: Fixed a regression in reloading sub-modules.
• ssl.create_default_context() sets OP_NO_COMPRESSION to prevent CRIME.
• Issue #19802: Add socket.SO_PRIORITY.
• Issue #11508: Fixed uuid.getnode() and uuid.uuid1() on environment with virtual interface. Original patch by Kent Frazier.
• Issue #11489: JSON decoder now accepts lone surrogates.
• Issue #19545: Avoid chained exceptions while passing stray % to time.strptime(). Initial patch by Claudiu Popa.

IDLE

• Issue #20058: sys.stdin.readline() in IDLE now always returns only one line.
• Issue #19481: print() of string subclass instance in IDLE no longer hangs.
• Issue #18270: Prevent possible IDLE AttributeError on OS X when no initial shell window is present.

Tests

• Issue #20055: Fix test_shutil under Windows with symlink privileges held. Patch by Vajrasky Kok.
• Issue #20070: Don’t run test_urllib2net when network resources are not enabled.
• Issue #19938: Re-enabled test_bug_1333982 in test_dis, which had been disabled since 3.0 due to the changes in listcomp handling.
• Issue #19320: test_tcl no longer fails when wantobjects is false.
• Issue #19919: Fix flaky SSL test. connect_ex() sometimes returns EWOULDBLOCK on Windows or VMs hosted on Windows.
• Issue #19912: Added tests for ntpath.splitunc().
• Issue #19828: Fixed test_site when the whole suite is run with -S.
• Issue #19928: Implemented a test for repr() of cell objects.
• Issue #19535: Fixed test_docxmlrpc, test_functools, test_inspect, and test_statistics when python is run with -OO.
• Issue #19926: Removed unneeded test_main from test_abstract_numbers. Patch by Vajrasky Kok.
• Issue #19572: More skipped tests explicitly marked as skipped.
• Issue #19595, #19987: Re-enabled a long-disabled test in test_winsound.
• Issue #19588: Fixed tests in test_random that were silently skipped most of the time. Patch by Julian Gindi.

Build

• Issue #19728: Enable pip installation by default on Windows.
• Issue #16136: Remove VMS support
• Issue #18215: Add script Tools/ssl/test_multiple_versions.py to compile and run Python’s unit tests with multiple versions of OpenSSL.
• Issue #19922: define _INCLUDE__STDC_A1_SOURCE in HP-UX to include mbstate_t for mbrtowc().
• Issue #19788: kill_python(_d).exe is now run as a PreBuildEvent on the pythoncore sub-project. This should prevent build errors due a previous build’s python(_d).exe still running.

Documentation

• Issue #20265: Updated some parts of the Using Windows document.
• Issue #20266: Updated some parts of the Windows FAQ.
• Issue #20255: Updated the about and bugs pages.
• Issue #20253: Fixed a typo in the ipaddress docs that advertised an illegal attribute name. Found by INADA Naoki.
• Issue #18840: Introduce the json module in the tutorial, and de-emphasize the pickle module.
• Issue #19845: Updated the Compiling Python on Windows section.
• Issue #19795: Improved markup of True/False constants.

Tools/Demos

• Issue #19659: Added documentation for Argument Clinic.
• Issue #19976: Argument Clinic METH_NOARGS functions now always take two parameters.

Core and Builtins

• Use the repr of a module name in more places in import, especially exceptions.
• Issue #19619: str.encode, bytes.decode and bytearray.decode now use an internal API to throw LookupError for known non-text encodings, rather than attempting the encoding or decoding operation and then throwing a TypeError for an unexpected output type. (The latter mechanism remains in place for third party non-text encodings)
• Issue #19183: Implement PEP 456 ‘secure and interchangeable hash algorithm’. Python now uses SipHash24 on all major platforms.
• Issue #12892: The utf-16* and utf-32* encoders no longer allow surrogate code points (U+D800-U+DFFF) to be encoded. The utf-32* decoders no longer decode byte sequences that correspond to surrogate code points. The surrogatepass error handler now works with the utf-16* and utf-32* codecs. Based on patches by Victor Stinner and Kang-Hao (Kenny) Lu.
• Issue #17806: Added keyword-argument support for “tabsize” to str/bytes.expandtabs().
• Issue #17828: Output type errors in str.encode(), bytes.decode() and bytearray.decode() now direct users to codecs.encode() or codecs.decode() as appropriate.
• Issue #17828: The interpreter now attempts to chain errors that occur in codec processing with a replacement exception of the same type that includes the codec name in the error message. It ensures it only does this when the creation of the replacement exception won’t lose any information.
• Issue #19466: Clear the frames of daemon threads earlier during the Python shutdown to call objects destructors. So “unclosed file” resource warnings are now corretly emitted for daemon threads.
• Issue #19514: Deduplicate some _Py_IDENTIFIER declarations. Patch by Andrei Dorian Duma.
• Issue #17936: Fix O(n**2) behaviour when adding or removing many subclasses of a given type.
• Issue #19428: zipimport now handles errors when reading truncated or invalid ZIP archive.
• Issue #18408: Add a new PyFrame_FastToLocalsWithError() function to handle exceptions when merging fast locals into f_locals of a frame. PyEval_GetLocals() now raises an exception and return NULL on failure.
• Issue #19369: Optimized the usage of __length_hint__().
• Issue #18603: Ensure that PyOS_mystricmp and PyOS_mystrnicmp are in the Python executable and not removed by the linker’s optimizer.
• Issue #19306: Add extra hints to the faulthandler module’s stack dumps that these are “upside down”.

Library

• Issue #3158: doctest can now find doctests in functions and methods written in C.
• Issue #13477: Added command line interface to the tarfile module. Original patch by Berker Peksag.
• Issue #19674: inspect.signature() now produces a correct signature for some builtins.
• Issue #19722: Added opcode.stack_effect(), which computes the stack effect of bytecode instructions.
• Issue #19735: Implement private function ssl._create_stdlib_context() to create SSLContext objects in Python’s stdlib module. It provides a single configuration point and makes use of SSLContext.load_default_certs().
• Issue #16203: Add re.fullmatch() function and regex.fullmatch() method, which anchor the pattern at both ends of the string to match. Original patch by Matthew Barnett.
• Issue #13592: Improved the repr for regular expression pattern objects. Based on patch by Hugo Lopes Tavares.
• Issue #19641: Added the audioop.byteswap() function to convert big-endian samples to little-endian and vice versa.
• Issue #15204: Deprecated the ‘U’ mode in file-like objects.
• Issue #17810: Implement PEP 3154, pickle protocol 4.
• Issue #19668: Added support for the cp1125 encoding.
• Issue #19689: Add ssl.create_default_context() factory function. It creates a new SSLContext object with secure default settings.
• Issue #19727: os.utime(..., None) is now potentially more precise under Windows.
• Issue #17201: ZIP64 extensions now are enabled by default. Patch by William Mallard.
• Issue #19292: Add SSLContext.load_default_certs() to load default root CA certificates from default stores or system stores. By default the method loads CA certs for authentication of server certs.
• Issue #19673: Add pathlib to the stdlib as a provisional module (PEP 428).
• Issue #16596: pdb in a generator now properly skips over yield and yield from rather than stepping out of the generator into its caller. (This is essential for stepping through asyncio coroutines.)
• Issue #17916: Added dis.Bytecode.from_traceback() and dis.Bytecode.current_offset to easily display “current instruction” markers in the new disassembly API (Patch by Claudiu Popa).
• Issue #19552: venv now supports bootstrapping pip into virtual environments
• Issue #17134: Finalize interface to Windows’ certificate store. Cert and CRL enumeration are now two functions. enum_certificates() also returns purpose flags as set of OIDs.
• Issue #19555: Restore sysconfig.get_config_var(‘SO’), (and the distutils equivalent) with a DeprecationWarning pointing people at $EXT_SUFFIX.
• Issue #8813: Add SSLContext.verify_flags to change the verification flags of the context in order to enable certification revocation list (CRL) checks or strict X509 rules.
• Issue #18294: Fix the zlib module to make it 64-bit safe.
• Issue #19682: Fix compatibility issue with old version of OpenSSL that was introduced by Issue #18379.
• Issue #14455: plistlib now supports binary plists and has an updated API.
• Issue #19633: Fixed writing not compressed 16- and 32-bit wave files on big-endian platforms.
• Issue #18379: SSLSocket.getpeercert() returns CA issuer AIA fields, OCSP and CRL distribution points.
• Issue #18138: Implement cadata argument of SSLContext.load_verify_location() to load CA certificates and CRL from memory. It supports PEM and DER encoded strings.
• Issue #18775: Add name and block_size attribute to HMAC object. They now provide the same API elements as non-keyed cryptographic hash functions.
• Issue #17276: MD5 as default digestmod for HMAC is deprecated. The HMAC module supports digestmod names, e.g. hmac.HMAC(‘sha1’).
• Issue #19449: in csv’s writerow, handle non-string keys when generating the error message that certain keys are not in the ‘fieldnames’ list.
• Issue #13633: Added a new convert_charrefs keyword arg to HTMLParser that, when True, automatically converts all character references.
• Issue #2927: Added the unescape() function to the html module.
• Issue #8402: Added the escape() function to the glob module.
• Issue #17618: Add Base85 and Ascii85 encoding/decoding to the base64 module.
• Issue #19634: time.strftime(“%y”) now raises a ValueError on AIX when given a year before 1900.
• Fix test.support.bind_port() to not cause an error when Python was compiled on a system with SO_REUSEPORT defined in the headers but run on a system with an OS kernel that does not support that reasonably new socket option.
• Fix compilation error under gcc of the ctypes module bundled libffi for arm.
• Issue #19448: Add private API to SSL module to lookup ASN.1 objects by OID, NID, short name and long name.
• Issue #19282: dbm.open now supports the context management protocol. (Inital patch by Claudiu Popa)
• Issue #8311: Added support for writing any bytes-like objects in the aifc, sunau, and wave modules.
• Issue #5202: Added support for unseekable files in the wave module.
• Issue #19544 and Issue #1180: Restore global option to ignore ~/.pydistutils.cfg in Distutils, accidentally removed in backout of distutils2 changes.
• Issue #19523: Closed FileHandler leak which occurred when delay was set.
• Issue #19544 and Issue #6516: Restore support for –user and –group parameters to sdist command accidentally rolled back as part of the distutils2 rollback.
• Issue #13674: Prevented time.strftime from crashing on Windows when given a year before 1900 and a format of %y.
• Issue #19406: implementation of the ensurepip module (part of PEP 453). Patch by Donald Stufft and Nick Coghlan.
• Issue #19544 and Issue #6286: Restore use of urllib over http allowing use of http_proxy for Distutils upload command, a feature accidentally lost in the rollback of distutils2.
• Issue #19544 and Issue #7457: Restore the read_pkg_file method to distutils.dist.DistributionMetadata accidentally removed in the undo of distutils2.
• Issue #16685: Added support for any bytes-like objects in the audioop module. Removed support for strings.
• Issue #7171: Add Windows implementation of inet_ntop and inet_pton to socket module. Patch by Atsuo Ishimoto.
• Issue #19261: Added support for writing 24-bit samples in the sunau module.
• Issue #1097797: Added CP273 encoding, used on IBM mainframes in Germany and Austria. Mapping provided by Michael Bierenfeld.
• Issue #1575020: Fixed support of 24-bit wave files on big-endian platforms.
• Issue #19378: Fixed a number of cases in the dis module where the new “file” parameter was not being honoured correctly
• Issue #19378: Removed the “dis.Bytecode.show_info” method
• Issue #19378: Renamed the “dis.Bytecode.display_code” method to “dis.Bytecode.dis” and converted it to returning a string rather than printing output.
• Issue #19378: the “line_offset” parameter in the new “dis.get_instructions” API has been renamed to “first_line” (and the default value and usage changed accordingly). This should reduce confusion with the more common use of “offset” in the dis docs to refer to bytecode offsets.
• Issue #18678: Corrected spwd struct member names in spwd module: sp_nam->sp_namp, and sp_pwd->sp_pwdp. The old names are kept as extra structseq members, for backward compatibility.
• Issue #6157: Fixed tkinter.Text.debug(). tkinter.Text.bbox() now raises TypeError instead of TclError on wrong number of arguments. Original patch by Guilherme Polo.
• Issue #10197: Rework subprocess.get[status]output to use subprocess functionality and thus to work on Windows. Patch by Nick Coghlan
• Issue #6160: The bbox() method of tkinter.Spinbox now returns a tuple of integers instead of a string. Based on patch by Guilherme Polo.
• Issue #19403: contextlib.redirect_stdout is now reentrant
• Issue #19286: Directories in package_data are no longer added to the filelist, preventing failure outlined in the ticket.
• Issue #19480: HTMLParser now accepts all valid start-tag names as defined by the HTML5 standard.
• Issue #15114: The html.parser module now raises a DeprecationWarning when the strict argument of HTMLParser or the HTMLParser.error method are used.
• Issue #19410: Undo the special-casing removal of ‘’ for importlib.machinery.FileFinder.
• Issue #19424: Fix the warnings module to accept filename containing surrogate characters.
• Issue #19435: Fix directory traversal attack on CGIHttpRequestHandler.
• Issue #19227: Remove pthread_atfork() handler. The handler was added to solve #18747 but has caused issues.
• Issue #19420: Fix reference leak in module initalization code of _hashopenssl.c
• Issue #19329: Optimized compiling charsets in regular expressions.
• Issue #19227: Try to fix deadlocks caused by re-seeding then OpenSSL pseudo-random number generator on fork().
• Issue #16037: HTTPMessage.readheaders() raises an HTTPException when more than 100 headers are read. Adapted from patch by Jyrki Pulliainen.
• Issue #16040: CVE-2013-1752: nntplib: Limit maximum line lengths to 2048 to prevent readline() calls from consuming too much memory. Patch by Jyrki Pulliainen.
• Issue #16041: CVE-2013-1752: poplib: Limit maximum line lengths to 2048 to prevent readline() calls from consuming too much memory. Patch by Jyrki Pulliainen.
• Issue #17997: Change behavior of ssl.match_hostname() to follow RFC 6125, for security reasons. It now doesn’t match multiple wildcards nor wildcards inside IDN fragments.
• Issue #16039: CVE-2013-1752: Change use of readline in imaplib module to limit line length. Patch by Emil Lind.
• Issue #19330: the unnecessary wrapper functions have been removed from the implementations of the new contextlib.redirect_stdout and contextlib.suppress context managers, which also ensures they provide reasonable help() output on instances
• Issue #19393: Fix symtable.symtable function to not be confused when there are functions or classes named “top”.
• Issue #18685: Restore re performance to pre-PEP 393 levels.
• Issue #19339: telnetlib module is now using time.monotonic() when available to compute timeout.
• Issue #19399: fix sporadic test_subprocess failure.
• Issue #13234: Fix os.listdir to work with extended paths on Windows. Patch by Santoso Wijaya.
• Issue #19375: The site module adding a “site-python” directory to sys.path, if it exists, is now deprecated.
• Issue #19379: Lazily import linecache in the warnings module, to make startup with warnings faster until a warning gets printed.
• Issue #19288: Fixed the “in” operator of dbm.gnu databases for string argument. Original patch by Arfrever Frehtes Taifersar Arahesis.
• Issue #19287: Fixed the “in” operator of dbm.ndbm databases for string argument. Original patch by Arfrever Frehtes Taifersar Arahesis.
• Issue #19327: Fixed the working of regular expressions with too big charset.
• Issue #17400: New ‘is_global’ attribute for ipaddress to tell if an address is allocated by IANA for global or private networks.
• Issue #19350: Increasing the test coverage of macurl2path. Patch by Colin Williams.
• Issue #19365: Optimized the parsing of long replacement string in re.sub*() functions.
• Issue #19352: Fix unittest discovery when a module can be reached through several paths (e.g. under Debian/Ubuntu with virtualenv).
• Issue #15207: Fix mimetypes to read from correct part of Windows registry Original patch by Dave Chambers
• Issue #16595: Add prlimit() to resource module.
• Issue #19324: Expose Linux-specific constants in resource module.
• Load SSL’s error strings in hashlib.
• Issue #18527: Upgrade internal copy of zlib to 1.2.8.
• Issue #19274: Add a filterfunc parameter to PyZipFile.writepy.
• Issue #8964: fix platform._sys_version to handle IronPython 2.6+. Patch by Martin Matusiak.
• Issue #19413: Restore pre-3.3 reload() semantics of re-finding modules.
• Issue #18958: Improve error message for json.load(s) while passing a string that starts with a UTF-8 BOM.
• Issue #19307: Improve error message for json.load(s) while passing objects of the wrong type.
• Issue #16038: CVE-2013-1752: ftplib: Limit amount of data read by limiting the call to readline(). Original patch by Michał Jastrzębski and Giampaolo Rodola.
• Issue #17087: Improved the repr for regular expression match objects.

Tests

• Issue #19664: test_userdict’s repr test no longer depends on the order of dict elements.
• Issue #19440: Clean up test_capi by removing an unnecessary __future__ import, converting from test_main to unittest.main, and running the _testcapi module tests as subTests of a unittest TestCase method.
• Issue #19378: the main dis module tests are now run with both stdout redirection and passing an explicit file parameter
• Issue #19378: removed the not-actually-helpful assertInstructionMatches and assertBytecodeExactlyMatches helpers from bytecode_helper
• Issue #18702: All skipped tests now reported as skipped.
• Issue #19439: interpreter embedding tests are now executed on Windows (Patch by Zachary Ware)
• Issue #19085: Added basic tests for all tkinter widget options.
• Issue #19384: Fix test_py_compile for root user, patch by Claudiu Popa.

Documentation

• Issue #18326: Clarify that list.sort’s arguments are keyword-only. Also, attempt to reduce confusion in the glossary by not saying there are different “types” of arguments and parameters.

Build

• Issue #19358: “make clinic” now runs the Argument Clinic preprocessor over all CPython source files.
• Update SQLite to 3.8.1, xz to 5.0.5, and Tcl/Tk to 8.6.1 on Windows.
• Issue #16632: Enable DEP and ASLR on Windows.
• Issue #17791: Drop PREFIX and EXEC_PREFIX definitions from PC/pyconfig.h
• Add workaround for VS 2010 nmake clean issue. VS 2010 doesn’t set up PATH for nmake.exe correctly.
• Issue #19550: Implement Windows installer changes of PEP 453 (ensurepip).
• Issue #19520: Fix compiler warning in the _sha3 module on 32bit Windows.
• Issue #19356: Avoid using a C variabled named “_self”, it’s a reserved word in some C compilers.
• Issue #15792: Correct build options on Win64. Patch by Jeremy Kloth.
• Issue #19373: Apply upstream change to Tk 8.5.15 fixing OS X 10.9 screen refresh problem for OS X installer build.
• Issue #19649: On OS X, the same set of file names are now installed in bin directories for all configurations: non-framework vs framework, and single arch vs universal builds. pythonx.y-32 is now always installed for 64-bit/32-bit universal builds. The obsolete and undocumented pythonw* symlinks are no longer installed anywhere.
• Issue #19553: PEP 453 - “make install” and “make altinstall” now install or upgrade pip by default, using the bundled pip provided by the new ensurepip module. A new configure option, –with-ensurepip[=upgrade|install|no], is available to override the default ensurepip “–upgrade” option. The option can also be set with “make [alt]install ENSUREPIP=[upgrade|installno]”.
• Issue #19551: PEP 453 - the OS X installer now installs pip by default.
• Update third-party libraries for OS X installers: xz 5.0.3 -> 5.0.5, SQLite 3.7.13 -> 3.8.1
• Issue #15663: Revert OS X installer built-in Tcl/Tk support for 3.4.0b1. Some third-party projects, such as Matplotlib and PIL/Pillow, depended on being able to build with Tcl and Tk frameworks in /Library/Frameworks.

Tools/Demos

• Issue #19730: Argument Clinic now supports all the existing PyArg “format units” as legacy converters, as well as two new features: “self converters” and the “version” directive.
• Issue #19552: pyvenv now bootstraps pip into virtual environments by default (pass –without-pip to request the old behaviour)
• Issue #19390: Argument Clinic no longer accepts malformed Python and C ids.

Core and Builtins

• Issue #19301: Give classes and functions that are explicitly marked global a global qualname.
• Issue #19279: UTF-7 decoder no longer produces illegal strings.
• Issue #16612: Add “Argument Clinic”, a compile-time preprocessor for C files to generate argument parsing code. (See PEP 436.)
• Issue #18810: Shift stat calls in importlib.machinery.FileFinder such that the code is optimistic that if something exists in a directory named exactly like the possible package being searched for that it’s in actuality a directory.
• Issue #18416: importlib.machinery.PathFinder now treats ‘’ as the cwd and importlib.machinery.FileFinder no longer special-cases ‘’ to ‘.’. This leads to modules imported from cwd to now possess an absolute file path for __file__ (this does not affect modules specified by path on the CLI but it does affect -m/runpy). It also allows FileFinder to be more consistent by not having an edge case.
• Issue #4555: All exported C symbols are now prefixed with either “Py” or “_Py”.
• Issue #19219: Speed up marshal.loads(), and make pyc files slightly (5% to 10%) smaller.
• Issue #19221: Upgrade Unicode database to version 6.3.0.
• Issue #16742: The result of the C callback PyOS_ReadlineFunctionPointer must now be a string allocated by PyMem_RawMalloc() or PyMem_RawRealloc() (or NULL if an error occurred), instead of a string allocated by PyMem_Malloc() or PyMem_Realloc().
• Issue #19199: Remove PyThreadState.tick_counter field
• Fix macro expansion of _PyErr_OCCURRED(), and make sure to use it in at least one place so as to avoid regressions.
• Issue #19087: Improve bytearray allocation in order to allow cheap popping of data at the front (slice deletion).
• Issue #19014: memoryview.cast() is now allowed on zero-length views.
• Issue #18690: memoryview is now automatically registered with collections.abc.Sequence
• Issue #19078: memoryview now correctly supports the reversed builtin (Patch by Claudiu Popa)

Library

• Issue #17457: unittest test discovery now works with namespace packages. Patch by Claudiu Popa.
• Issue #18235: Fix the sysconfig variables LDSHARED and BLDSHARED under AIX. Patch by David Edelsohn.
• Issue #18606: Add the new “statistics” module (PEP 450). Contributed by Steven D’Aprano.
• Issue #12866: The audioop module now supports 24-bit samples.
• Issue #19254: Provide an optimized Python implementation of pbkdf2_hmac.
• Issues #19201, Issue #19222, Issue #19223: Add “x” mode (exclusive creation) in opening file to bz2, gzip and lzma modules. Patches by Tim Heaney and Vajrasky Kok.
• Fix a reference count leak in _sre.
• Issue #19262: Initial check in of the ‘asyncio’ package (a.k.a. Tulip, a.k.a. PEP 3156). There are no docs yet, and the PEP is slightly out of date with the code. This module will have provisional status in Python 3.4.
• Issue #19276: Fixed the wave module on 64-bit big-endian platforms.
• Issue #19266: Rename the new-in-3.4 contextlib.ignore context manager to contextlib.suppress in order to be more consistent with existing descriptions of that operation elsewhere in the language and standard library documentation (Patch by Zero Piraeus).
• Issue #18891: Completed the new email package (provisional) API additions by adding new classes EmailMessage, MIMEPart, and ContentManager.
• Issue #18281: Unused stat constants removed from tarfile.
• Issue #18999: Multiprocessing now supports ‘contexts’ with the same API as the module, but bound to specified start methods.
• Issue #18468: The re.split, re.findall, and re.sub functions and the group() and groups() methods of match object now always return a string or a bytes object.
• Issue #18725: The textwrap module now supports truncating multiline text.
• Issue #18776: atexit callbacks now display their full traceback when they raise an exception.
• Issue #17827: Add the missing documentation for codecs.encode and codecs.decode.
• Issue #19218: Rename collections.abc to _collections_abc in order to speed up interpreter start.
• Issue #18582: Add ‘pbkdf2_hmac’ to the hashlib module. It implements PKCS#5 password-based key derivation functions with HMAC as pseudorandom function.
• Issue #19131: The aifc module now correctly reads and writes sampwidth of compressed streams.
• Issue #19209: Remove import of copyreg from the os module to speed up interpreter startup. stat_result and statvfs_result are now hard-coded to reside in the os module.
• Issue #19205: Don’t import the ‘re’ module in site and sysconfig module to speed up interpreter start.
• Issue #9548: Add a minimal “_bootlocale” module that is imported by the _io module instead of the full locale module.
• Issue #18764: Remove the ‘print’ alias for the PDB ‘p’ command so that it no longer shadows the print function.
• Issue #19158: A rare race in BoundedSemaphore could allow .release() too often.
• Issue #15805: Add contextlib.redirect_stdout().
• Issue #18716: Deprecate the formatter module.
• Issue #10712: 2to3 has a new “asserts” fixer that replaces deprecated names of unittest methods (e.g. failUnlessEqual -> assertEqual).
• Issue #18037: 2to3 now escapes ‘u’ and ‘U’ in native strings.
• Issue #17839: base64.decodebytes and base64.encodebytes now accept any object that exports a 1 dimensional array of bytes (this means the same is now also true for base64_codec)
• Issue #19132: The pprint module now supports compact mode.
• Issue #19137: The pprint module now correctly formats instances of set and frozenset subclasses.
• Issue #10042: functools.total_ordering now correctly handles NotImplemented being returned by the underlying comparison function (Patch by Katie Miller)
• Issue #19092: contextlib.ExitStack now correctly reraises exceptions from the __exit__ callbacks of inner context managers (Patch by Hrvoje Nikšić)
• Issue #12641: Avoid passing “-mno-cygwin” to the mingw32 compiler, except when necessary. Patch by Oscar Benjamin.
• Issue #5845: In site.py, only load readline history from ~/.python_history if no history has been read already. This avoids double writes to the history file at shutdown.
• Properly initialize all fields of a SSL object after allocation.
• Issue #19095: SSLSocket.getpeercert() now raises ValueError when the SSL handshake hasn’t been done.
• Issue #4366: Fix building extensions on all platforms when –enable-shared is used.
• Issue #19030: Fixed inspect.getmembers and inspect.classify_class_attrs to attempt activating descriptors before falling back to a __dict__ search for faulty descriptors. inspect.classify_class_attrs no longer returns Attributes whose home class is None.

C API

• Issue #1772673: The type of char* arguments now changed to const char*.
• Issue #16129: Added a Py_SetStandardStreamEncoding pre-initialization API to allow embedding applications like Blender to force a particular encoding and error handler for the standard IO streams (initial patch by Bastien Montagne)

Tests

• Issue #19275: Fix test_site on AMD64 Snow Leopard
• Issue #14407: Fix unittest test discovery in test_concurrent_futures.
• Issue #18919: Unified and extended tests for audio modules: aifc, sunau and wave.
• Issue #18714: Added tests for pdb.find_function().

Documentation

• Issue #18758: Fixed and improved cross-references.
• Issue #18972: Modernize email examples and use the argparse module in them.

Build

• Issue #19130: Correct PCbuild/readme.txt, Python 3.3 and 3.4 require VS 2010.

• Issue #15663: Update OS X 10.6+ installer to use Tcl/Tk 8.5.15.

• Issue #14499: Fix several problems with OS X universal build support:

  1. ppc arch detection for extension module builds broke with Xcode 5
  2. ppc arch detection in configure did not work on OS X 10.4
  3. -sysroot and -arch flags were unnecessarily duplicated
  4. there was no obvious way to configure an intel-32 only build.

• Issue #19019: Change the OS X installer build script to use CFLAGS instead of OPT for special build options. By setting OPT, some compiler-specific options like -fwrapv were overridden and thus not used, which could result in broken interpreters when building with clang.

Core and Builtins

• Issue #18818: The “encodingname” part of PYTHONIOENCODING is now optional.
• Issue #19098: Prevent overflow in the compiler when the recursion limit is set absurdly high.

Library

• Issue #18929: inspect.classify_class_attrs() now correctly finds class attributes returned by dir() that are located in the metaclass.
• Issue #18950: Fix miscellaneous bugs in the sunau module. Au_read.readframes() now updates current file position and reads correct number of frames from multichannel stream. Au_write.writeframesraw() now correctly updates current file position. Au_read.getnframes() now returns an integer (as in Python 2). Au_read and Au_write now correctly works with file object if start file position is not a zero.
• Issue #18594: The fast path for collections.Counter() was never taken due to an over-restrictive type check.
• Issue #19053: ZipExtFile.read1() with non-zero argument no more returns empty bytes until end of data.
• logging: added support for Unix domain sockets to SocketHandler and DatagramHandler.
• Issue #18996: TestCase.assertEqual() now more cleverly shorten differing strings in error report.
• Issue #19034: repr() for tkinter.Tcl_Obj now exposes string reperesentation.
• Issue #18978: urllib.request.Request now allows the method to be indicated on the class and no longer sets it to None in __init__.
• Issue #18626: the inspect module now offers a basic command line introspection interface (Initial patch by Claudiu Popa)
• Issue #3015: Fixed tkinter with wantobject=False. Any Tcl command call returned empty string.
• Issue #19037: The mailbox module now makes all changes to maildir files before moving them into place, to avoid race conditions with other programs that may be accessing the maildir directory.
• Issue #14984: On POSIX systems, when netrc is called without a filename argument (and therefore is reading the user’s $HOME/.netrc file), it now enforces the same security rules as typical ftp clients: the .netrc file must be owned by the user that owns the process and must not be readable by any other user.
• Issue #18873: The tokenize module now detects Python source code encoding only in comment lines.
• Issue #17764: Enable http.server to bind to a user specified network interface. Patch contributed by Malte Swart.
• Issue #18937: Add an assertLogs() context manager to unittest.TestCase to ensure that a block of code emits a message using the logging module.
• Issue #17324: Fix http.server’s request handling case on trailing ‘/’. Patch contributed by Vajrasky Kok.
• Issue #19018: The heapq.merge() function no longer suppresses IndexError in the underlying iterables.
• Issue #18784: The uuid module no longer attempts to load libc via ctypes.CDLL if all the necessary functions have already been found in libuuid. Patch by Evgeny Sologubov.
• The PYTHONFAULTHANDLER environment variable now only enables the faulthandler module if the variable is non-empty. Same behaviour than other variables like PYTHONDONTWRITEBYTECODE.
• Issue #1565525: New function traceback.clear_frames will clear the local variables of all the stack frames referenced by a traceback object.

Tests

• Issue #18952: Fix regression in support data downloads introduced when test.support was converted to a package. Regression noticed by Zachary Ware.

IDLE

• Issue #18873: IDLE now detects Python source code encoding only in comment lines.
• Issue #18988: The “Tab” key now works when a word is already autocompleted.

Documentation

• Issue #17003: Unified the size argument names in the io module with common practice.

Build

• Issue #18596: Support the use of address sanity checking in recent versions of clang and GCC by appropriately marking known false alarms in the small object allocator. Patch contributed by Dhiru Kholia.

Tools/Demos

• Issue #18873: 2to3 and the findnocoding.py script now detect Python source code encoding only in comment lines.

Core and Builtins

• Issue #18942: sys._debugmallocstats() output was damaged on Windows.
• Issue #18571: Implementation of the PEP 446: file descriptors and file handles are now created non-inheritable; add functions os.get/set_inheritable(), os.get/set_handle_inheritable() and socket.socket.get/set_inheritable().
• Issue #11619: The parser and the import machinery do not encode Unicode filenames anymore on Windows.
• Issue #18808: Non-daemon threads are now automatically joined when a sub-interpreter is shutdown (it would previously dump a fatal error).
• Remove support for compiling on systems without getcwd().
• Issue #18774: Remove last bits of GNU PTH thread code and thread_pth.h.
• Issue #18771: Add optimization to set object lookups to reduce the cost of hash collisions. The core idea is to inspect a second key/hash pair for each cache line retrieved.
• Issue #16105: When a signal handler fails to write to the file descriptor registered with signal.set_wakeup_fd(), report an exception instead of ignoring the error.
• Issue #18722: Remove uses of the “register” keyword in C code.
• Issue #18667: Add missing “HAVE_FCHOWNAT” symbol to posix._have_functions.
• Issue #16499: Add command line option for isolated mode.
• Issue #15301: Parsing fd, uid, and gid parameters for builtins in Modules/posixmodule.c is now far more robust.
• Issue #18368: PyOS_StdioReadline() no longer leaks memory when realloc() fail.
• Issue #17934: Add a clear() method to frame objects, to help clean up expensive details (local variables) and break reference cycles.
• Issue #18780: %-formatting codes %d, %i, and %u now treat int-subclasses as int (displays value of int-subclass instead of str(int-subclass) ).

Library

• Issue #18808: Thread.join() now waits for the underlying thread state to be destroyed before returning. This prevents unpredictable aborts in Py_EndInterpreter() when some non-daemon threads are still running.
• Issue #18458: Prevent crashes with newer versions of libedit. Its readline emulation has changed from 0-based indexing to 1-based like gnu readline.
• Issue #18852: Handle case of readline.__doc__ being None in the new readline activation code in site.py.
• Issue #18672: Fixed format specifiers for Py_ssize_t in debugging output in the _sre module.
• Issue #18830: inspect.getclasstree() no longer produces duplicate entries even when input list contains duplicates.
• Issue #18878: sunau.open now supports the context management protocol. Based on patches by Claudiu Popa and R. David Murray.
• Issue #18909: Fix _tkinter.tkapp.interpaddr() on Windows 64-bit, don’t cast 64-bit pointer to long (32 bits).
• Issue #18876: The FileIO.mode attribute now better reflects the actual mode under which the file was opened. Patch by Erik Bray.
• Issue #16853: Add new selectors module.
• Issue #18882: Add threading.main_thread() function.
• Issue #18901: The sunau getparams method now returns a namedtuple rather than a plain tuple. Patch by Claudiu Popa.
• Issue #17487: The result of the wave getparams method now is pickleable again. Patch by Claudiu Popa.
• Issue #18756: os.urandom() now uses a lazily-opened persistent file descriptor, so as to avoid using many file descriptors when run in parallel from multiple threads.
• Issue #18418: After fork(), reinit all threads states, not only active ones. Patch by A. Jesse Jiryu Davis.
• Issue #17974: Switch unittest from using getopt to using argparse.
• Issue #11798: TestSuite now drops references to own tests after execution.
• Issue #16611: http.cookie now correctly parses the ‘secure’ and ‘httponly’ cookie flags.
• Issue #11973: Fix a problem in kevent. The flags and fflags fields are now properly handled as unsigned.
• Issue #18807: pyvenv now takes a –copies argument allowing copies instead of symlinks even where symlinks are available and the default.
• Issue #18538: python -m dis now uses argparse for argument processing. Patch by Michele Orrù.
• Issue #18394: Close cgi.FieldStorage’s optional file.
• Issue #17702: On error, os.environb now suppresses the exception context when raising a new KeyError with the original key.
• Issue #16809: Fixed some tkinter incompabilities with Tcl/Tk 8.6.
• Issue #16809: Tkinter’s splitlist() and split() methods now accept Tcl_Obj argument.
• Issue #18324: set_payload now correctly handles binary input. This also supersedes the previous fixes for #14360, #1717, and #16564.
• Issue #18794: Add a fileno() method and a closed attribute to select.devpoll objects.
• Issue #17119: Fixed integer overflows when processing large strings and tuples in the tkinter module.
• Issue #18747: Re-seed OpenSSL’s pseudo-random number generator after fork. A pthread_atfork() parent handler is used to seed the PRNG with pid, time and some stack data.
• Issue #8865: Concurrent invocation of select.poll.poll() now raises a RuntimeError exception. Patch by Christian Schubert.
• Issue #18777: The ssl module now uses the new CRYPTO_THREADID API of OpenSSL 1.0.0+ instead of the deprecated CRYPTO id callback function.
• Issue #18768: Correct doc string of RAND_edg(). Patch by Vajrasky Kok.
• Issue #18178: Fix ctypes on BSD. dlmalloc.c was compiled twice which broke malloc weak symbols.
• Issue #18709: Fix CVE-2013-4238. The SSL module now handles NULL bytes inside subjectAltName correctly. Formerly the module has used OpenSSL’s GENERAL_NAME_print() function to get the string represention of ASN.1 strings for rfc822Name (email), dNSName (DNS) and uniformResourceIdentifier (URI).
• Issue #18701: Remove support of old CPython versions (<3.0) from C code.
• Issue #18756: Improve error reporting in os.urandom() when the failure is due to something else than /dev/urandom not existing (for example, exhausting the file descriptor limit).
• Issue #18673: Add O_TMPFILE to os module. O_TMPFILE requires Linux kernel 3.11 or newer. It’s only defined on system with 3.11 uapi headers, too.
• Issue #18532: Change the builtin hash algorithms’ names to lower case names as promised by hashlib’s documentation.
• Issue #8713: add new spwan and forkserver start methods, and new functions get_all_start_methods, get_start_method, and set_start_method, to multiprocessing.
• Issue #18405: Improve the entropy of crypt.mksalt().
• Issue #12015: The tempfile module now uses a suffix of 8 random characters instead of 6, to reduce the risk of filename collision. The entropy was reduced when uppercase letters were removed from the charset used to generate random characters.
• Issue #18585: Add textwrap.shorten() to collapse and truncate a piece of text to a given length.
• Issue #18598: Tweak exception message for importlib.import_module() to include the module name when a key argument is missing.
• Issue #19151: Fix docstring and use of _get_supported_file_loaders() to reflect 2-tuples.
• Issue #19152: Add ExtensionFileLoader.get_filename().
• Issue #18676: Change ‘positive’ to ‘non-negative’ in queue.py put and get docstrings and ValueError messages. Patch by Zhongyue Luo
• Fix refcounting issue with extension types in tkinter.
• Issue #8112: xlmrpc.server’s DocXMLRPCServer server no longer raises an error if methods have annotations; it now correctly displays the annotations.
• Issue #18600: Added policy argument to email.message.Message.as_string, and as_bytes and __bytes__ methods to Message.
• Issue #18671: Output more information when logging exceptions occur.
• Issue #18621: Prevent the site module’s patched builtins from keeping too many references alive for too long.
• Issue #4885: Add weakref support to mmap objects. Patch by Valerie Lambert.
• Issue #8860: Fixed rounding in timedelta constructor.
• Issue #18849: Fixed a Windows-specific tempfile bug where collision with an existing directory caused mkstemp and related APIs to fail instead of retrying. Report and fix by Vlad Shcherbina.
• Issue #18920: argparse’s default destination for the version action (-v, –version) has also been changed to stdout, to match the Python executable.

Tests

• Issue #18623: Factor out the _SuppressCoreFiles context manager into test.support. Patch by Valerie Lambert.
• Issue #12037: Fix test_email for desktop Windows.
• Issue #15507: test_subprocess’s test_send_signal could fail if the test runner were run in an environment where the process inherited an ignore setting for SIGINT. Restore the SIGINT handler to the desired KeyboardInterrupt raising one during that test.
• Issue #16799: Switched from getopt to argparse style in regrtest’s argument parsing. Added more tests for regrtest’s argument parsing.
• Issue #18792: Use “127.0.0.1” or ”::1” instead of “localhost” as much as possible, since “localhost” goes through a DNS lookup under recent Windows versions.

IDLE

• Issue #18489: Add tests for SearchEngine. Original patch by Phil Webster.

Documentation

• Issue #18743: Fix references to non-existant “StringIO” module.
• Issue #18783: Removed existing mentions of Python long type in docstrings, error messages and comments.

Build

• Issue #1584: Provide configure options to override default search paths for Tcl and Tk when building _tkinter.
• Issue #15663: Tcl/Tk 8.5.14 is now included with the OS X 10.6+ 64-/32-bit installer. It is no longer necessary to install a third-party version of Tcl/Tk 8.5 to work around the problems in the Apple-supplied Tcl/Tk 8.5 shipped in OS X 10.6 and later releases.

Tools/Demos

• Issue #18922: Now The Lib/smtpd.py and Tools/i18n/msgfmt.py scripts write their version strings to stdout, and not to sderr.

Core and Builtins

• Issue #16741: Fix an error reporting in int().
• Issue #17899: Fix rare file descriptor leak in os.listdir().
• Issue #10241: Clear extension module dict copies at interpreter shutdown. Patch by Neil Schemenauer, minimally modified.
• Issue #9035: ismount now recognises volumes mounted below a drive root on Windows. Original patch by Atsuo Ishimoto.
• Issue #18214: Improve finalization of Python modules to avoid setting their globals to None, in most cases.
• Issue #18112: PEP 442 implementation (safe object finalization).
• Issue #18552: Check return value of PyArena_AddPyObject() in obj2ast_object().
• Issue #18560: Fix potential NULL pointer dereference in sum().
• Issue #18520: Add a new PyStructSequence_InitType2() function, same than PyStructSequence_InitType() except that it has a return value (0 on success, -1 on error).
• Issue #15905: Fix theoretical buffer overflow in handling of sys.argv[0], prefix and exec_prefix if the operation system does not obey MAXPATHLEN.
• Issue #18408: Fix many various bugs in code handling errors, especially on memory allocation failure (MemoryError).
• Issue #18344: Fix potential ref-leaks in _bufferedreader_read_all().
• Issue #18342: Use the repr of a module name when an import fails when using from ... import ....
• Issue #17872: Fix a segfault in marshal.load() when input stream returns more bytes than requested.
• Issue #18338: python --version now prints version string to stdout, and not to stderr. Patch by Berker Peksag and Michael Dickens.
• Issue #18426: Fix NULL pointer dereference in C extension import when PyModule_GetDef() returns an error.
• Issue #17206: On Windows, increase the stack size from 2 MB to 4.2 MB to fix a stack overflow in the marshal module (fix a crash in test_marshal). Patch written by Jeremy Kloth.
• Issue #3329: Implement the PEP 445: Add new APIs to customize Python memory allocators.
• Issue #18328: Reorder ops in PyThreadState_Delete*() functions. Now the tstate is first removed from TLS and then deallocated.
• Issue #13483: Use VirtualAlloc in obmalloc on Windows.
• Issue #18184: PyUnicode_FromFormat() and PyUnicode_FromFormatV() now raise OverflowError when an argument of %c format is out of range.
• Issue #18111: The min() and max() functions now support a default argument to be returned instead of raising a ValueError on an empty sequence. (Contributed by Julian Berman.)
• Issue #18137: Detect integer overflow on precision in float.__format__() and complex.__format__().
• Issue #18183: Fix various unicode operations on strings with large unicode codepoints.
• Issue #18180: Fix ref leak in _PyImport_GetDynLoadWindows().
• Issue #18038: SyntaxError raised during compilation sources with illegal encoding now always contains an encoding name.
• Issue #17931: Resolve confusion on Windows between pids and process handles.
• Tweak the exception message when the magic number or size value in a bytecode file is truncated.
• Issue #17932: Fix an integer overflow issue on Windows 64-bit in iterators: change the C type of seqiterobject.it_index from long to Py_ssize_t.
• Issue #18065: Don’t set __path__ to the package name for frozen packages.
• Issue #18088: When reloading a module, unconditionally reset all relevant attributes on the module (e.g. __name__, __loader__, __package__, __file__, __cached__).
• Issue #17937: Try harder to collect cyclic garbage at shutdown.
• Issue #12370: Prevent class bodies from interfering with the __class__ closure.
• Issue #17644: Fix a crash in str.format when curly braces are used in square brackets.
• Issue #17237: Fix crash in the ASCII decoder on m68k.
• Issue #17927: Frame objects kept arguments alive if they had been copied into a cell, even if the cell was cleared.
• Issue #1545463: At shutdown, defer finalization of codec modules so that stderr remains usable.
• Issue #7330: Implement width and precision (ex: “%5.3s”) for the format string of PyUnicode_FromFormat() function, original patch written by Ysj Ray.
• Issue #1545463: Global variables caught in reference cycles are now garbage-collected at shutdown.
• Issue #17094: Clear stale thread states after fork(). Note that this is a potentially disruptive change since it may release some system resources which would otherwise remain perpetually alive (e.g. database connections kept in thread-local storage).
• Issue #17408: Avoid using an obsolete instance of the copyreg module when the interpreter is shutdown and then started again.
• Issue #5845: Enable tab-completion in the interactive interpreter by default, thanks to a new sys.__interactivehook__.
• Issue #17115,17116: Module initialization now includes setting __package__ and __loader__ attributes to None.
• Issue #17853: Ensure locals of a class that shadow free variables always win over the closures.
• Issue #17863: In the interactive console, don’t loop forever if the encoding can’t be fetched from stdin.
• Issue #17867: Raise an ImportError if __import__ is not found in __builtins__.
• Issue #18698: Ensure importlib.reload() returns the module out of sys.modules.
• Issue #17857: Prevent build failures with pre-3.5.0 versions of sqlite3, such as was shipped with Centos 5 and Mac OS X 10.4.
• Issue #17413: sys.settrace callbacks were being passed a string instead of an exception instance for the ‘value’ element of the arg tuple if the exception originated from C code; now an exception instance is always provided.
• Issue #17782: Fix undefined behaviour on platforms where struct timespec‘s “tv_nsec” member is not a C long.
• Issue #17722: When looking up __round__, resolve descriptors.
• Issue #16061: Speed up str.replace() for replacing 1-character strings.
• Issue #17715: Fix segmentation fault from raising an exception in a __trunc__ method.
• Issue #17643: Add __callback__ attribute to weakref.ref.
• Issue #16447: Fixed potential segmentation fault when setting __name__ on a class.
• Issue #17669: Fix crash involving finalization of generators using yield from.
• Issue #14439: Python now prints the traceback on runpy failure at startup.
• Issue #17469: Fix _Py_GetAllocatedBlocks() and sys.getallocatedblocks() when running on valgrind.
• Issue #17619: Make input() check for Ctrl-C correctly on Windows.
• Issue #17357: Add missing verbosity messages for -v/-vv that were lost during the importlib transition.
• Issue #17610: Don’t rely on non-standard behavior of the C qsort() function.
• Issue #17323: The “[X refs, Y blocks]” printed by debug builds has been disabled by default. It can be re-enabled with the -X showrefcount option.
• Issue #17328: Fix possible refleak in dict.setdefault.
• Issue #17275: Corrected class name in init error messages of the C version of BufferedWriter and BufferedRandom.
• Issue #7963: Fixed misleading error message that issued when object is called without arguments.
• Issue #8745: Small speed up zipimport on Windows. Patch by Catalin Iacob.
• Issue #5308: Raise ValueError when marshalling too large object (a sequence with size >= 2**31), instead of producing illegal marshal data.
• Issue #12983: Bytes literals with invalid x escape now raise a SyntaxError and a full traceback including line number.
• Issue #16967: In function definition, evaluate positional defaults before keyword-only defaults.
• Issue #17173: Remove uses of locale-dependent C functions (isalpha() etc.) in the interpreter.
• Issue #17137: When an Unicode string is resized, the internal wide character string (wstr) format is now cleared.
• Issue #17043: The unicode-internal decoder no longer read past the end of input buffer.
• Issue #17098: All modules now have __loader__ set even if they pre-exist the bootstrapping of importlib.
• Issue #16979: Fix error handling bugs in the unicode-escape-decode decoder.
• Issue #16772: The base argument to the int constructor no longer accepts floats, or other non-integer objects with an __int__ method. Objects with an __index__ method are now accepted.
• Issue #10156: In the interpreter’s initialization phase, unicode globals are now initialized dynamically as needed.
• Issue #16980: Fix processing of escaped non-ascii bytes in the unicode-escape-decode decoder.
• Issue #16975: Fix error handling bug in the escape-decode bytes decoder.
• Issue #14850: Now a charmap decoder treats U+FFFE as “undefined mapping” in any mapping, not only in a string.
• Issue #16613: Add m argument to collections.Chainmap.new_child to allow the new child map to be specified explicitly.
• Issue #16730: importlib.machinery.FileFinder now no longers raises an exception when trying to populate its cache and it finds out the directory is unreadable or has turned into a file. Reported and diagnosed by David Pritchard.
• Issue #16906: Fix a logic error that prevented most static strings from being cleared.
• Issue #11461: Fix the incremental UTF-16 decoder. Original patch by Amaury Forgeot d’Arc.
• Issue #16856: Fix a segmentation fault from calling repr() on a dict with a key whose repr raise an exception.
• Issue #16367: Fix FileIO.readall() on Windows for files larger than 2 GB.
• Issue #16761: Calling int() with base argument only now raises TypeError.
• Issue #16759: Support the full DWORD (unsigned long) range in Reg2Py when retrieving a REG_DWORD value. This corrects functions like winreg.QueryValueEx that may have been returning truncated values.
• Issue #14420: Support the full DWORD (unsigned long) range in Py2Reg when passed a REG_DWORD value. Fixes OverflowError in winreg.SetValueEx.
• Issue #11939: Set the st_dev attribute of stat_result to allow Windows to take advantage of the os.path.samefile/sameopenfile/samestat implementations used by other platforms.
• Issue #16772: The int() constructor’s second argument (base) no longer accepts non integer values. Consistent with the behavior in Python 2.
• Issue #14470: Remove w9xpopen support per PEP 11.
• Issue #9856: Replace deprecation warning with raising TypeError in object.__format__. Patch by Florent Xicluna.
• Issue #16597: In buffered and text IO, call close() on the underlying stream if invoking flush() fails.
• Issue #16722: In the bytes() constructor, try to call __bytes__ on the argument before __index__.
• Issue #16421: loading multiple modules from one shared object is now handled correctly (previously, the first module loaded from that file was silently returned). Patch by Václav Šmilauer.
• Issue #16602: When a weakref’s target was part of a long deallocation chain, the object could remain reachable through its weakref even though its refcount had dropped to zero.
• Issue #16495: Remove extraneous NULL encoding check from bytes_decode().
• Issue #16619: Create NameConstant AST class to represent None, True, and False literals. As a result, these constants are never loaded at runtime from builtins.
• Issue #16455: On FreeBSD and Solaris, if the locale is C, the ASCII/surrogateescape codec is now used (instead of the locale encoding) to decode the command line arguments. This change fixes inconsistencies with os.fsencode() and os.fsdecode(), because these operating systems announce an ASCII locale encoding, but actually use the ISO-8859-1 encoding in practice.
• Issue #16562: Optimize dict equality testing. Patch by Serhiy Storchaka.
• Issue #16588: Silence unused-but-set warnings in Python/thread_pthread
• Issue #16592: stringlib_bytes_join doesn’t raise MemoryError on allocation failure.
• Issue #16546: Fix: ast.YieldFrom argument is now mandatory.
• Issue #16514: Fix regression causing a traceback when sys.path[0] is None (actually, any non-string or non-bytes type).
• Issue #16306: Fix multiple error messages when unknown command line parameters where passed to the interpreter. Patch by Hieu Nguyen.
• Issue #16215: Fix potential double memory free in str.replace(). Patch by Serhiy Storchaka.
• Issue #16290: A float return value from the __complex__ special method is no longer accepted in the complex() constructor.
• Issue #16416: On Mac OS X, operating system data are now always encoded/decoded to/from UTF-8/surrogateescape, instead of the locale encoding (which may be ASCII if no locale environment variable is set), to avoid inconsistencies with os.fsencode() and os.fsdecode() functions which are already using UTF-8/surrogateescape.
• Issue #16453: Fix equality testing of dead weakref objects.
• Issue #9535: Fix pending signals that have been received but not yet handled by Python to not persist after os.fork() in the child process.
• Issue #14794: Fix slice.indices to return correct results for huge values, rather than raising OverflowError.
• Issue #15001: fix segfault on “del sys.modules[‘__main__’]”. Patch by Victor Stinner.
• Issue #8271: the utf-8 decoder now outputs the correct number of U+FFFD characters when used with the ‘replace’ error handler on invalid utf-8 sequences. Patch by Serhiy Storchaka, tests by Ezio Melotti.
• Issue #5765: Apply a hard recursion limit in the compiler instead of blowing the stack and segfaulting. Initial patch by Andrea Griffini.
• Issue #16402: When slicing a range, fix shadowing of exceptions from __index__.
• Issue #16336: fix input checking in the surrogatepass error handler. Patch by Serhiy Storchaka.
• Issue #8401: assigning an int to a bytearray slice (e.g. b[3:4] = 5) now raises an error.
• Issue #7317: Display full tracebacks when an error occurs asynchronously. Patch by Alon Horev with update by Alexey Kachayev.
• Issue #16309: Make PYTHONPATH=”” behavior the same as if PYTHONPATH not set at all.
• Issue #10189: Improve the error reporting of SyntaxErrors related to global and nonlocal statements.
• Fix segfaults on setting __qualname__ on builtin types and attempting to delete it on any type.
• Issue #14625: Rewrite the UTF-32 decoder. It is now 3x to 4x faster. Patch written by Serhiy Storchaka.
• Issue #16345: Fix an infinite loop when fromkeys on a dict subclass received a nonempty dict from the constructor.
• Issue #16271: Fix strange bugs that resulted from __qualname__ appearing in a class’s __dict__ and on type.
• Issue #12805: Make bytes.join and bytearray.join faster when the separator is empty. Patch by Serhiy Storchaka.
• Issue #6074: Ensure cached bytecode files can always be updated by the user that created them, even when the source file is read-only.
• Issue #15958: bytes.join and bytearray.join now accept arbitrary buffer objects.
• Issue #14783: Improve int() docstring and switch docstrings for str(), range(), and slice() to use multi-line signatures.
• Issue #16160: Subclass support now works for types.SimpleNamespace.
• Issue #16148: Implement PEP 424, adding operator.length_hint and PyObject_LengthHint.
• Upgrade Unicode data (UCD) to version 6.2.
• Issue #15379: Fix passing of non-BMP characters as integers for the charmap decoder (already working as unicode strings). Patch by Serhiy Storchaka.
• Issue #15144: Fix possible integer overflow when handling pointers as integer values, by using Py_uintptr_t instead of size_t. Patch by Serhiy Storchaka.
• Issue #15965: Explicitly cast AT_FDCWD as (int). Required on Solaris 10 (which defines AT_FDCWD as 0xffd19553), harmless on other platforms.
• Issue #15839: Convert SystemErrors in super() to RuntimeErrors.
• Issue #15448: Buffered IO now frees the buffer when closed, instead of when deallocating.
• Issue #15846: Fix SystemError which happened when using ast.parse() in an exception handler on code with syntax errors.
• Issue #15897: zipimport.c doesn’t check return value of fseek(). Patch by Felipe Cruz.
• Issue #15801: Make sure mappings passed to ‘%’ formatting are actually subscriptable.
• Issue #15111: __import__ should propagate ImportError when raised as a side-effect of a module triggered from using fromlist.
• Issue #15022: Add pickle and comparison support to types.SimpleNamespace.

Library

• Issue #4331: Added functools.partialmethod (Initial patch by Alon Horev)
• Issue #13461: Fix a crash in the TextIOWrapper.tell method on 64-bit platforms. Patch by Yogesh Chaudhari.
• Issue #18681: Fix a NameError in importlib.reload() (noticed by Weizhao Li).
• Issue #14323: Expanded the number of digits in the coefficients for the RGB – YIQ conversions so that they match the FCC NTSC versions.
• Issue #17998: Fix an internal error in regular expression engine.
• Issue #17557: Fix os.getgroups() to work with the modified behavior of getgroups(2) on OS X 10.8. Original patch by Mateusz Lenik.
• Issue #18608: Avoid keeping a strong reference to the locale module inside the _io module.
• Issue #18619: Fix atexit leaking callbacks registered from sub-interpreters, and make it GC-aware.
• Issue #15699: The readline module now uses PEP 3121-style module initialization, so as to reclaim allocated resources (Python callbacks) at shutdown. Original patch by Robin Schreiber.
• Issue #17616: wave.open now supports the context management protocol.
• Issue #18599: Fix name attribute of _sha1.sha1() object. It now returns ‘SHA1’ instead of ‘SHA’.
• Issue #13266: Added inspect.unwrap to easily unravel __wrapped__ chains (initial patch by Daniel Urban and Aaron Iles)
• Issue #18561: Skip name in ctypes’ _build_callargs() if name is NULL.
• Issue #18559: Fix NULL pointer dereference error in _pickle module
• Issue #18556: Check the return type of PyUnicode_AsWideChar() in ctype’s U_set().
• Issue #17818: aifc.getparams now returns a namedtuple.
• Issue #18549: Eliminate dead code in socket_ntohl()
• Issue #18530: Remove additional stat call from posixpath.ismount. Patch by Alex Gaynor.
• Issue #18514: Fix unreachable Py_DECREF() call in PyCData_FromBaseObj()
• Issue #9177: Calling read() or write() now raises ValueError, not AttributeError, on a closed SSL socket. Patch by Senko Rasic.
• Issue #18513: Fix behaviour of cmath.rect w.r.t. signed zeros on OS X 10.8 + gcc.
• Issue #18479: Changed venv Activate.ps1 to make deactivate a function, and removed Deactivate.ps1.
• Issue #18480: Add missing call to PyType_Ready to the _elementtree extension.
• Issue #17778: Fix test discovery for test_multiprocessing. (Patch by Zachary Ware.)
• Issue #18393: The private module _gestalt and private functions platform._mac_ver_gestalt, platform._mac_ver_lookup and platform._bcd2str have been removed. This does not affect the public interface of the platform module.
• Issue #17482: functools.update_wrapper (and functools.wraps) now set the __wrapped__ attribute correctly even if the underlying function has a __wrapped__ attribute set.
• Issue #18431: The new email header parser now decodes RFC2047 encoded words in structured headers.
• Issue #18432: The sched module’s queue method was incorrectly returning an iterator instead of a list.
• Issue #18044: The new email header parser was mis-parsing encoded words where an encoded character immediately followed the ‘?’ that follows the CTE character, resulting in a decoding failure. They are now decoded correctly.
• Issue #18101: Tcl.split() now process strings nested in a tuple as it do with byte strings.
• Issue #18116: getpass was always getting an error when testing /dev/tty, and thus was always falling back to stdin, and would then raise an exception if stdin could not be used (such as /dev/null). It also leaked an open file. All of these issues are now fixed.
• Issue #17198: Fix a NameError in the dbm module. Patch by Valentina Mukhamedzhanova.
• Issue #18013: Fix cgi.FieldStorage to parse the W3C sample form.
• Issue #18020: improve html.escape speed by an order of magnitude. Patch by Matt Bryant.
• Issue #18347: ElementTree’s html serializer now preserves the case of closing tags.
• Issue #17261: Ensure multiprocessing’s proxies use proper address.
• Issue #18343: faulthandler.register() now keeps the previous signal handler when the function is called twice, so faulthandler.unregister() restores correctly the original signal handler.
• Issue #17097: Make multiprocessing ignore EINTR.
• Issue #18339: Negative ints keys in unpickler.memo dict no longer cause a segfault inside the _pickle C extension.
• Issue #18240: The HMAC module is no longer restricted to bytes and accepts any bytes-like object, e.g. memoryview. Original patch by Jonas Borgström.
• Issue #18224: Removed pydoc script from created venv, as it causes problems on Windows and adds no value over and above python -m pydoc ...
• Issue #18155: The csv module now correctly handles csv files that use a delimter character that has a special meaning in regexes, instead of throwing an exception.
• Issue #14360: encode_quopri can now be successfully used as an encoder when constructing a MIMEApplication object.
• Issue #11390: Add -o and -f command line options to the doctest CLI to specify doctest options (and convert it to using argparse).
• Issue #18135: ssl.SSLSocket.write() now raises an OverflowError if the input string in longer than 2 gigabytes, and ssl.SSLContext.load_cert_chain() raises a ValueError if the password is longer than 2 gigabytes. The ssl module does not support partial write.
• Issue #11016: Add C implementation of the stat module as _stat.
• Issue #18248: Fix libffi build on AIX.
• Issue #18259: Declare sethostname in socketmodule.c for AIX
• Issue #18147: Add diagnostic functions to ssl.SSLContext(). get_ca_list() lists all loaded CA certificates and cert_store_stats() returns amount of loaded X.509 certs, X.509 CA certs and CRLs.
• Issue #18167: cgi.FieldStorage no longer fails to handle multipart/form-data when rn appears at end of 65535 bytes without other newlines.
• Issue #18076: Introduce importlib.util.decode_source().
• Issue #18357: add tests for dictview set difference. Patch by Fraser Tweedale.
• importlib.abc.SourceLoader.get_source() no longer changes SyntaxError or UnicodeDecodeError into ImportError.
• Issue #18058, 18057: Make the namespace package loader meet the importlib.abc.InspectLoader ABC, allowing for namespace packages to work with runpy.
• Issue #17177: The imp module is pending deprecation.
• subprocess: Prevent a possible double close of parent pipe fds when the subprocess exec runs into an error. Prevent a regular multi-close of the /dev/null fd when any of stdin, stdout and stderr was set to DEVNULL.
• Issue #18194: Introduce importlib.util.cache_from_source() and source_from_cache() while documenting the equivalent functions in imp as deprecated.
• Issue #17907: Document imp.new_module() as deprecated in favour of types.ModuleType.
• Issue #18192: Introduce importlib.util.MAGIC_NUMBER and document as deprecated imp.get_magic().
• Issue #18149: Add filecmp.clear_cache() to manually clear the filecmp cache. Patch by Mark Levitt
• Issue #18193: Add importlib.reload().
• Issue #18157: Stop using imp.load_module() in pydoc.
• Issue #16102: Make uuid._netbios_getnode() work again on Python 3.
• Issue #17134: Add ssl.enum_cert_store() as interface to Windows’ cert store.
• Issue #18143: Implement ssl.get_default_verify_paths() in order to debug the default locations for cafile and capath.
• Issue #17314: Move multiprocessing.forking over to importlib.
• Issue #11959: SMTPServer and SMTPChannel now take an optional map, use of which avoids affecting global state.
• Issue #18109: os.uname() now decodes fields from the locale encoding, and socket.gethostname() now decodes the hostname from the locale encoding, instead of using the UTF-8 encoding in strict mode.
• Issue #18089: Implement importlib.abc.InspectLoader.load_module.
• Issue #18088: Introduce importlib.abc.Loader.init_module_attrs for setting module attributes. Leads to the pending deprecation of importlib.util.module_for_loader.
• Issue #17403: urllib.parse.robotparser normalizes the urls before adding to ruleline. This helps in handling certain types invalid urls in a conservative manner. Patch contributed by Mher Movsisyan.
• Issue #18070: Have importlib.util.module_for_loader() set attributes unconditionally in order to properly support reloading.
• Added importlib.util.module_to_load to return a context manager to provide the proper module object to load.
• Issue #18025: Fixed a segfault in io.BufferedIOBase.readinto() when raw stream’s read() returns more bytes than requested.
• Issue #18011: As was originally intended, base64.b32decode() now raises a binascii.Error if there are non-b32-alphabet characters present in the input string, instead of a TypeError.
• Issue #18072: Implement importlib.abc.InspectLoader.get_code() and importlib.abc.ExecutionLoader.get_code().
• Issue #8240: Set the SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER flag on SSL sockets.
• Issue #17269: Workaround for socket.getaddrinfo crash on MacOS X with port None or “0” and flags AI_NUMERICSERV.
• Issue #16986: ElementTree now correctly works with string input when the internal XML encoding is not UTF-8 or US-ASCII.
• Issue #17996: socket module now exposes AF_LINK constant on BSD and OSX.
• Issue #17900: Allowed pickling of recursive OrderedDicts. Decreased pickled size and pickling time.
• Issue #17914: Add os.cpu_count(). Patch by Yogesh Chaudhari, based on an initial patch by Trent Nelson.
• Issue #17812: Fixed quadratic complexity of base64.b32encode(). Optimize base64.b32encode() and base64.b32decode() (speed up to 3x).
• Issue #17980: Fix possible abuse of ssl.match_hostname() for denial of service using certificates with many wildcards (CVE-2013-2099).
• Issue #15758: Fix FileIO.readall() so it no longer has O(n**2) complexity.
• Issue #14596: The struct.Struct() objects now use a more compact implementation.
• Issue #17981: logging’s SysLogHandler now closes the socket when it catches socket OSErrors.
• Issue #17964: Fix os.sysconf(): the return type of the C sysconf() function is long, not int.
• Fix typos in the multiprocessing module.
• Issue #17754: Make ctypes.util.find_library() independent of the locale.
• Issue #17968: Fix memory leak in os.listxattr().
• Issue #17606: Fixed support of encoded byte strings in the XMLGenerator characters() and ignorableWhitespace() methods. Original patch by Sebastian Ortiz Vasquez.
• Issue #17732: Ignore distutils.cfg options pertaining to install paths if a virtual environment is active.
• Issue #17915: Fix interoperability of xml.sax with file objects returned by codecs.open().
• Issue #16601: Restarting iteration over tarfile really restarts rather than continuing from where it left off. Patch by Michael Birtwell.
• Issue #17289: The readline module now plays nicer with external modules or applications changing the rl_completer_word_break_characters global variable. Initial patch by Bradley Froehle.
• Issue #12181: select module: Fix struct kevent definition on OpenBSD 64-bit platforms. Patch by Federico Schwindt.
• Issue #11816: multiple improvements to the dis module: get_instructions generator, ability to redirect output to a file, Bytecode and Instruction abstractions. Patch by Nick Coghlan, Ryan Kelly and Thomas Kluyver.
• Issue #13831: Embed stringification of remote traceback in local traceback raised when pool task raises an exception.
• Issue #15528: Add weakref.finalize to support finalization using weakref callbacks.
• Issue #14173: Avoid crashing when reading a signal handler during interpreter shutdown.
• Issue #15902: Fix imp.load_module() accepting None as a file when loading an extension module.
• Issue #13721: SSLSocket.getpeercert() and SSLSocket.do_handshake() now raise an OSError with ENOTCONN, instead of an AttributeError, when the SSLSocket is not connected.
• Issue #14679: add an __all__ (that contains only HTMLParser) to html.parser.
• Issue #17802: Fix an UnboundLocalError in html.parser. Initial tests by Thomas Barlow.
• Issue #17358: Modules loaded by imp.load_source() and load_compiled() (and by extention load_module()) now have a better chance of working when reloaded.
• Issue #17804: New function struct.iter_unpack allows for streaming struct unpacking.
• Issue #17830: When keyword.py is used to update a keyword file, it now preserves the line endings of the original file.
• Issue #17272: Making the urllib.request’s Request.full_url a descriptor. Fixes bugs with assignment to full_url. Patch by Demian Brecht.
• Issue #17353: Plistlib emitted empty data tags with deeply nested datastructures
• Issue #11714: Use ‘with’ statements to assure a Semaphore releases a condition variable. Original patch by Thomas Rachel.
• Issue #16624: subprocess.check_output now accepts an input argument, allowing the subprocess’s stdin to be provided as a (byte) string. Patch by Zack Weinberg.
• Issue #17795: Reverted backwards-incompatible change in SysLogHandler with Unix domain sockets.
• Issue #16694: Add a pure Python implementation of the operator module. Patch by Zachary Ware.
• Issue #11182: remove the unused and undocumented pydoc.Scanner class. Patch by Martin Morrison.
• Issue #17741: Add ElementTree.XMLPullParser, an event-driven parser for non-blocking applications.
• Issue #17555: Fix ForkAwareThreadLock so that size of after fork registry does not grow exponentially with generation of process.
• Issue #17707: fix regression in multiprocessing.Queue’s get() method where it did not block for short timeouts.
• Issue #17720: Fix the Python implementation of pickle.Unpickler to correctly process the APPENDS opcode when it is used on non-list objects.
• Issue #17012: shutil.which() no longer falls back to the PATH environment variable if an empty path argument is specified. Patch by Serhiy Storchaka.
• Issue #17710: Fix pickle raising a SystemError on bogus input.
• Issue #17341: Include the invalid name in the error messages from re about invalid group names.
• Issue #17702: os.environ now raises KeyError with the original environment variable name (str on UNIX), instead of using the encoded name (bytes on UNIX).
• Issue #16163: Make the importlib based version of pkgutil.iter_importers work for submodules. Initial patch by Berker Peksag.
• Issue #16804: Fix a bug in the ‘site’ module that caused running ‘python -S -m site’ to incorrectly throw an exception.
• Issue #15480: Remove the deprecated and unused TYPE_INT64 code from marshal. Initial patch by Daniel Riti.
• Issue #2118: SMTPException is now a subclass of OSError.
• Issue #17016: Get rid of possible pointer wraparounds and integer overflows in the re module. Patch by Nickolai Zeldovich.
• Issue #16658: add missing return to HTTPConnection.send() Patch by Jeff Knupp.
• Issue #9556: the logging package now allows specifying a time-of-day for a TimedRotatingFileHandler to rotate.
• Issue #14971: unittest test discovery no longer gets confused when a function has a different __name__ than its name in the TestCase class dictionary.
• Issue #17487: The wave getparams method now returns a namedtuple rather than a plain tuple.
• Issue #17675: socket repr() provides local and remote addresses (if any). Patch by Giampaolo Rodola’
• Issue #17093: Make the ABCs in importlib.abc provide default values or raise reasonable exceptions for their methods to make them more amenable to super() calls.
• Issue #17566: Make importlib.abc.Loader.module_repr() optional instead of an abstractmethod; now it raises NotImplementedError so as to be ignored by default.
• Issue #17678: Remove the use of deprecated method in http/cookiejar.py by changing the call to get_origin_req_host() to origin_req_host.
• Issue #17666: Fix reading gzip files with an extra field.
• Issue #16475: Support object instancing, recursion and interned strings in marshal
• Issue #17502: Process DEFAULT values in mock side_effect that returns iterator.
• Issue #16795: On the ast.arguments object, unify vararg with varargannotation and kwarg and kwargannotation. Change the column offset of ast.Attribute to be at the attribute name.
• Issue #17434: Properly raise a SyntaxError when a string occurs between future imports.
• Issue #17117: Import and @importlib.util.set_loader now set __loader__ when it has a value of None or the attribute doesn’t exist.
• Issue #17032: The “global” in the “NameError: global name ‘x’ is not defined” error message has been removed. Patch by Ram Rachum.
• Issue #18080: When building a C extension module on OS X, if the compiler is overriden with the CC environment variable, use the new compiler as the default for linking if LDSHARED is not also overriden. This restores Distutils behavior introduced in 3.2.3 and inadvertently dropped in 3.3.0.
• Issue #18113: Fixed a refcount leak in the curses.panel module’s set_userptr() method. Reported by Atsuo Ishimoto.
• Implement PEP 443 “Single-dispatch generic functions”.
• Implement PEP 435 “Adding an Enum type to the Python standard library”.
• Issue #15596: Faster pickling of unicode strings.
• Issue #17572: Avoid chained exceptions when passing bad directives to time.strptime(). Initial patch by Claudiu Popa.
• Issue #17435: threading.Timer’s __init__ method no longer uses mutable default values for the args and kwargs parameters.
• Issue #17526: fix an IndexError raised while passing code without filename to inspect.findsource(). Initial patch by Tyler Doyle.
• Issue #17540: Added style parameter to logging formatter configuration by dict.
• Issue #16692: The ssl module now supports TLS 1.1 and TLS 1.2. Initial patch by Michele Orrù.
• Issue #17025: multiprocessing: Reduce Queue and SimpleQueue contention.
• Issue #17536: Add to webbrowser’s browser list: www-browser, x-www-browser, iceweasel, iceape.
• Issue #17150: pprint now uses line continuations to wrap long string literals.
• Issue #17488: Change the subprocess.Popen bufsize parameter default value from unbuffered (0) to buffering (-1) to match the behavior existing code expects and match the behavior of the subprocess module in Python 2 to avoid introducing hard to track down bugs.
• Issue #17521: Corrected non-enabling of logger following two calls to fileConfig().
• Issue #17508: Corrected logging MemoryHandler configuration in dictConfig() where the target handler wasn’t configured first.
• Issue #17209: curses.window.get_wch() now correctly handles KeyboardInterrupt (CTRL+c).
• Issue #5713: smtplib now handles 421 (closing connection) error codes when sending mail by closing the socket and reporting the 421 error code via the exception appropriate to the command that received the error response.
• Issue #16997: unittest.TestCase now provides a subTest() context manager to procedurally generate, in an easy way, small test instances.
• Issue #17485: Also delete the Request Content-Length header if the data attribute is deleted. (Follow on to issue Issue #16464).
• Issue #15927: CVS now correctly parses escaped newlines and carriage when parsing with quoting turned off.
• Issue #17467: add readline and readlines support to mock_open in unittest.mock.
• Issue #13248: removed deprecated and undocumented difflib.isbjunk, isbpopular.
• Issue #17192: Update the ctypes module’s libffi to v3.0.13. This specifically addresses a stack misalignment issue on x86 and issues on some more recent platforms.
• Issue #8862: Fixed curses cleanup when getkey is interrputed by a signal.
• Issue #17443: imaplib.IMAP4_stream was using the default unbuffered IO in subprocess, but the imap code assumes buffered IO. In Python2 this worked by accident. IMAP4_stream now explicitly uses buffered IO.
• Issue #17476: Fixed regression relative to Python2 in undocumented pydoc ‘allmethods’; it was missing unbound methods on the class.
• Issue #17474: Remove the deprecated methods of Request class.
• Issue #16709: unittest discover order is no-longer filesystem specific. Patch by Jeff Ramnani.
• Use the HTTPS PyPI url for upload, overriding any plain HTTP URL in pypirc.
• Issue #5024: sndhdr.whichhdr now returns the frame count for WAV files rather than -1.
• Issue #17460: Remove the strict argument of HTTPConnection and removing the DeprecationWarning being issued from 3.2 onwards.
• Issue #16880: Do not assume _imp.load_dynamic() is defined in the imp module.
• Issue #16389: Fixed a performance regression relative to Python 3.1 in the caching of compiled regular expressions.
• Added missing FeedParser and BytesFeedParser to email.parser.__all__.
• Issue #17431: Fix missing import of BytesFeedParser in email.parser.
• Issue #12921: http.server’s send_error takes an explain argument to send more information in response. Patch contributed by Karl.
• Issue #17414: Add timeit, repeat, and default_timer to timeit.__all__.
• Issue #1285086: Get rid of the refcounting hack and speed up urllib.parse.unquote() and urllib.parse.unquote_to_bytes().
• Issue #17099: Have importlib.find_loader() raise ValueError when __loader__ is not set, harmonizing with what happens when the attribute is set to None.
• Expose the O_PATH constant in the os module if it is available.
• Issue #17368: Fix an off-by-one error in the Python JSON decoder that caused a failure while decoding empty object literals when object_pairs_hook was specified.
• Issue #17385: Fix quadratic behavior in threading.Condition. The FIFO queue now uses a deque instead of a list.
• Issue #15806: Add contextlib.ignore(). This creates a context manager to ignore specified exceptions, replacing the “except SomeException: pass” idiom.
• Issue #14645: The email generator classes now produce output using the specified linesep throughout. Previously if the prolog, epilog, or body were stored with a different linesep, that linesep was used. This fix corrects an RFC non-compliance issue with smtplib.send_message.
• Issue #17278: Fix a crash in heapq.heappush() and heapq.heappop() when the list is being resized concurrently.
• Issue #16962: Use getdents64 instead of the obsolete getdents syscall in the subprocess module on Linux.
• Issue #16935: unittest now counts the module as skipped if it raises SkipTest, instead of counting it as an error. Patch by Zachary Ware.
• Issue #17018: Make Process.join() retry if os.waitpid() fails with EINTR.
• Issue #17223: array module: Fix a crasher when converting an array containing invalid characters (outside range [U+0000; U+10ffff]) to Unicode: repr(array), str(array) and array.tounicode(). Patch written by Manuel Jacob.
• Issue #17197: profile/cProfile modules refactored so that code of run() and runctx() utility functions is not duplicated in both modules.
• Issue #14720: sqlite3: Convert datetime microseconds correctly. Patch by Lowe Thiderman.
• Issue #15132: Allow a list for the defaultTest argument of unittest.TestProgram. Patch by Jyrki Pulliainen.
• Issue #17225: JSON decoder now counts columns in the first line starting with 1, as in other lines.
• Issue #6623: Added explicit DeprecationWarning for ftplib.netrc, which has been deprecated and undocumented for a long time.
• Issue #13700: Fix byte/string handling in imaplib authentication when an authobject is specified.
• Issue #13153: Tkinter functions now raise TclError instead of ValueError when a string argument contains non-BMP character.
• Issue #9669: Protect re against infinite loops on zero-width matching in non-greedy repeat. Patch by Matthew Barnett.
• Issue #13169: The maximal repetition number in a regular expression has been increased from 65534 to 2147483647 (on 32-bit platform) or 4294967294 (on 64-bit).
• Issue #17143: Fix a missing import in the trace module. Initial patch by Berker Peksag.
• Issue #15220: email.feedparser’s line splitting algorithm is now simpler and faster.
• Issue #16743: Fix mmap overflow check on 32 bit Windows.
• Issue #16996: webbrowser module now uses shutil.which() to find a web-browser on the executable search path.
• Issue #16800: tempfile.gettempdir() no longer left temporary files when the disk is full. Original patch by Amir Szekely.
• Issue #17192: Import libffi-3.0.12.
• Issue #16564: Fixed regression relative to Python2 in the operation of email.encoders.encode_7or8bit when used with binary data.
• Issue #17052: unittest discovery should use self.testLoader.
• Issue #4591: Uid and gid values larger than 2**31 are supported now.
• Issue #17141: random.vonmisesvariate() no longer hangs for large kappas.
• Issue #17149: Fix random.vonmisesvariate to always return results in [0, 2*math.pi].
• Issue #1470548: XMLGenerator now works with binary output streams.
• Issue #6975: os.path.realpath() now correctly resolves multiple nested symlinks on POSIX platforms.
• Issue #13773: sqlite3.connect() gets a new uri parameter to pass the filename as a URI, allowing to pass custom options.
• Issue #16564: Fixed regression relative to Python2 in the operation of email.encoders.encode_noop when used with binary data.
• Issue #10355: The mode, name, encoding and newlines properties now work on SpooledTemporaryFile objects even when they have not yet rolled over. Obsolete method xreadline (which has never worked in Python 3) has been removed.
• Issue #16686: Fixed a lot of bugs in audioop module. Fixed crashes in avgpp(), maxpp() and ratecv(). Fixed an integer overflow in add(), bias(), and ratecv(). reverse(), lin2lin() and ratecv() no more lose precision for 32-bit samples. max() and rms() no more returns a negative result and various other functions now work correctly with 32-bit sample -0x80000000.
• Issue #17073: Fix some integer overflows in sqlite3 module.
• Issue #16723: httplib.HTTPResponse no longer marked closed when the connection is automatically closed.
• Issue #15359: Add CAN_BCM protocol support to the socket module. Patch by Brian Thorne.
• Issue #16948: Fix quoted printable body encoding for non-latin1 character sets in the email package.
• Issue #16811: Fix folding of headers with no value in the provisional email policies.
• Issue #17132: Update symbol for “yield from” grammar changes.
• Issue #17076: Make copying of xattrs more tolerant of missing FS support. Patch by Thomas Wouters.
• Issue #17089: Expat parser now correctly works with string input when the internal XML encoding is not UTF-8 or US-ASCII. It also now accepts bytes and strings larger than 2 GiB.
• Issue #6083: Fix multiple segmentation faults occured when PyArg_ParseTuple parses nested mutating sequence.
• Issue #5289: Fix ctypes.util.find_library on Solaris.
• Issue #17106: Fix a segmentation fault in io.TextIOWrapper when an underlying stream or a decoder produces data of an unexpected type (i.e. when io.TextIOWrapper initialized with text stream or use bytes-to-bytes codec).
• Issue #17015: When it has a spec, a Mock object now inspects its signature when matching calls, so that arguments can be matched positionally or by name.
• Issue #15633: httplib.HTTPResponse is now mark closed when the server sends less than the advertised Content-Length.
• Issue #12268: The io module file object write methods no longer abort early when one of its write system calls is interrupted (EINTR).
• Issue #6972: The zipfile module no longer overwrites files outside of its destination path when extracting malicious zip files.
• Issue #4844: ZipFile now raises BadZipFile when opens a ZIP file with an incomplete “End of Central Directory” record. Original patch by Guilherme Polo and Alan McIntyre.
• Issue #17071: Signature.bind() now works when one of the keyword arguments is named self.
• Issue #12004: Fix an internal error in PyZipFile when writing an invalid Python file. Patch by Ben Morgan.
• Have py_compile use importlib as much as possible to avoid code duplication. Code now raises FileExistsError if the file path to be used for the byte-compiled file is a symlink or non-regular file as a warning that import will not keep the file path type if it writes to that path.
• Issue #16972: Have site.addpackage() consider already known paths even when none are explicitly passed in. Bug report and fix by Kirill.
• Issue #1602133: on Mac OS X a shared library build (--enable-shared) now fills the os.environ variable correctly.
• Issue #15505: unittest.installHandler no longer assumes SIGINT handler is set to a callable object.
• Issue #13454: Fix a crash when deleting an iterator created by itertools.tee() if all other iterators were very advanced before.
• Issue #12411: Fix to cgi.parse_multipart to correctly use bytes boundaries and bytes data. Patch by Jonas Wagner.
• Issue #16957: shutil.which() no longer searches a bare file name in the current directory on Unix and no longer searches a relative file path with a directory part in PATH directories. Patch by Thomas Kluyver.
• Issue #1159051: GzipFile now raises EOFError when reading a corrupted file with truncated header or footer.
• Issue #16993: shutil.which() now preserves the case of the path and extension on Windows.
• Issue #16992: On Windows in signal.set_wakeup_fd, validate the file descriptor argument.
• Issue #16422: For compatibility with the Python version, the C version of decimal now uses strings instead of integers for rounding mode constants.
• Issue #15861: tkinter now correctly works with lists and tuples containing strings with whitespaces, backslashes or unbalanced braces.
• Issue #9720: zipfile now writes correct local headers for files larger than 4 GiB.
• Issue #16955: Fix the poll() method for multiprocessing’s socket connections on Windows.
• SSLContext.load_dh_params() now properly closes the input file.
• Issue #15031: Refactor some .pyc management code to cut down on code duplication. Thanks to Ronan Lamy for the report and taking an initial stab at the problem.
• Issue #16398: Optimize deque.rotate() so that it only moves pointers and doesn’t touch the underlying data with increfs and decrefs.
• Issue #16900: Issue a ResourceWarning when an ssl socket is left unclosed.
• Issue #13899: A, Z, and B now correctly match the A, Z, and B literals when used inside character classes (e.g. ‘[A]’). Patch by Matthew Barnett.
• Issue #15545: Fix regression in sqlite3’s iterdump method where it was failing if the connection used a row factory (such as sqlite3.Row) that produced unsortable objects. (Regression was introduced by fix for 9750).
• fcntl: add F_DUPFD_CLOEXEC constant, available on Linux 2.6.24+.
• Issue #15972: Fix error messages when os functions expecting a file name or file descriptor receive the incorrect type.
• Issue #8109: The ssl module now has support for server-side SNI, thanks to a SSLContext.set_servername_callback() method. Patch by Daniel Black.
• Issue #16860: In tempfile, use O_CLOEXEC when available to set the close-on-exec flag atomically.
• Issue #16674: random.getrandbits() is now 20-40% faster for small integers.
• Issue #16009: JSON error messages now provide more information.
• Issue #16828: Fix error incorrectly raised by bz2.compress(b’‘) and bz2.BZ2Compressor.compress(b’‘). Initial patch by Martin Packman.
• Issue #16833: In http.client.HTTPConnection, do not concatenate the request headers and body when the payload exceeds 16 KB, since it can consume more memory for no benefit. Patch by Benno Leslie.
• Issue #16541: tk_setPalette() now works with keyword arguments.
• Issue #16820: In configparser, parser.popitem() no longer raises ValueError. This makes parser.clean() work correctly.
• Issue #16820: In configparser, parser['section'] = {} now preserves section order within the parser. This makes parser.update() preserve section order as well.
• Issue #16820: In configparser, parser['DEFAULT'] = {} now correctly clears previous values stored in the default section. Same goes for parser.update({'DEFAULT': {}}).
• Issue #9586: Redefine SEM_FAILED on MacOSX to keep compiler happy.
• Issue #16787: Increase asyncore and asynchat default output buffers size, to decrease CPU usage and increase throughput.
• Issue #10527: make multiprocessing use poll() instead of select() if available.
• Issue #16688: Now regexes contained backreferences correctly work with non-ASCII strings. Patch by Matthew Barnett.
• Issue #16486: Make aifc files act as context managers.
• Issue #16485: Now file descriptors are closed if file header patching failed on closing an aifc file.
• Issue #16640: Run less code under a lock in sched module.
• Issue #16165: sched.scheduler.run() no longer blocks a scheduler for other threads.
• Issue #16641: Default values of sched.scheduler.enter() are no longer modifiable.
• Issue #16618: Make glob.glob match consistently across strings and bytes regarding leading dots. Patch by Serhiy Storchaka.
• Issue #16788: Add samestat to Lib/ntpath.py
• Issue #16713: Parsing of ‘tel’ urls using urlparse separates params from path.
• Issue #16443: Add docstrings to regular expression match objects. Patch by Anton Kasyanov.
• Issue #15701: Fix HTTPError info method call to return the headers information.
• Issue #16752: Add a missing import to modulefinder. Patch by Berker Peksag.
• Issue #16646: ftplib.FTP.makeport() might lose socket error details. (patch by Serhiy Storchaka)
• Issue #16626: Fix infinite recursion in glob.glob() on Windows when the pattern contains a wildcard in the drive or UNC path. Patch by Serhiy Storchaka.
• Issue #15783: Except for the number methods, the C version of decimal now supports all None default values present in decimal.py. These values were largely undocumented.
• Issue #11175: argparse.FileType now accepts encoding and errors arguments. Patch by Lucas Maystre.
• Issue #16488: epoll() objects now support the with statement. Patch by Serhiy Storchaka.
• Issue #16298: In HTTPResponse.read(), close the socket when there is no Content-Length and the incoming stream is finished. Patch by Eran Rundstein.
• Issue #16049: Add abc.ABC class to enable the use of inheritance to create ABCs, rather than the more cumbersome metaclass=ABCMeta. Patch by Bruno Dupuis.
• Expose the TCP_FASTOPEN and MSG_FASTOPEN flags in socket when they’re available.
• Issue #15701: Add a .headers attribute to urllib.error.HTTPError. Patch contributed by Berker Peksag.
• Issue #15872: Fix 3.3 regression introduced by the new fd-based shutil.rmtree that caused it to not ignore certain errors when ignore_errors was set. Patch by Alessandro Moura and Serhiy Storchaka.
• Issue #16248: Disable code execution from the user’s home directory by tkinter when the -E flag is passed to Python. Patch by Zachary Ware.
• Issue #13390: New function sys.getallocatedblocks() returns the number of memory blocks currently allocated.
• Issue #16628: Fix a memory leak in ctypes.resize().
• Issue #13614: Fix setup.py register failure with invalid rst in description. Patch by Julien Courteau and Pierre Paul Lefebvre.
• Issue #13512: Create ~/.pypirc securely (CVE-2011-4944). Initial patch by Philip Jenvey, tested by Mageia and Debian.
• Issue #7719: Make distutils ignore .nfs* files instead of choking later on. Initial patch by SilentGhost and Jeff Ramnani.
• Issue #13120: Allow to call pdb.set_trace() from thread. Patch by Ilya Sandler.
• Issue #16585: Make CJK encoders support error handlers that return bytes per PEP 383.
• Issue #10182: The re module doesn’t truncate indices to 32 bits anymore. Patch by Serhiy Storchaka.
• Issue #16333: use (”,”, ”: ”) as default separator in json when indent is specified, to avoid trailing whitespace. Patch by Serhiy Storchaka.
• Issue #16573: In 2to3, treat enumerate() like a consuming call, so superfluous list() calls aren’t added to filter(), map(), and zip() which are directly passed enumerate().
• Issue #16464: Reset the Content-Length header when a urllib Request is reused with new data.
• Issue #12848: The pure Python pickle implementation now treats object lengths as unsigned 32-bit integers, like the C implementation does. Patch by Serhiy Storchaka.
• Issue #16423: urllib.request now has support for data: URLs. Patch by Mathias Panzenböck.
• Issue #4473: Add a POP3.stls() to switch a clear-text POP3 session into an encrypted POP3 session, on supported servers. Patch by Lorenzo Catucci.
• Issue #4473: Add a POP3.capa() method to query the capabilities advertised by the POP3 server. Patch by Lorenzo Catucci.
• Issue #4473: Ensure the socket is shutdown cleanly in POP3.close(). Patch by Lorenzo Catucci.
• Issue #16522: added FAIL_FAST flag to doctest.
• Issue #15627: Add the importlib.abc.InspectLoader.source_to_code() method.
• Issue #16408: Fix file descriptors not being closed in error conditions in the zipfile module. Patch by Serhiy Storchaka.
• Issue #14631: Add a new weakref.WeakMethod to simulate weak references to bound methods.
• Issue #16469: Fix exceptions from float -> Fraction and Decimal -> Fraction conversions for special values to be consistent with those for float -> int and Decimal -> int. Patch by Alexey Kachayev.
• Issue #16481: multiprocessing no longer leaks process handles on Windows.
• Issue #12428: Add a pure Python implementation of functools.partial(). Patch by Brian Thorne.
• Issue #16140: The subprocess module no longer double closes its child subprocess.PIPE parent file descriptors on child error prior to exec().
• Remove a bare print to stdout from the subprocess module that could have happened if the child process wrote garbage to its pre-exec error pipe.
• The subprocess module now raises its own SubprocessError instead of a RuntimeError in various error situations which should not normally happen.
• Issue #16327: The subprocess module no longer leaks file descriptors used for stdin/stdout/stderr pipes to the child when fork() fails.
• Issue #14396: Handle the odd rare case of waitpid returning 0 when not expected in subprocess.Popen.wait().
• Issue #16411: Fix a bug where zlib.decompressobj().flush() might try to access previously-freed memory. Patch by Serhiy Storchaka.
• Issue #16357: fix calling accept() on a SSLSocket created through SSLContext.wrap_socket(). Original patch by Jeff McNeil.
• Issue #16409: The reporthook callback made by the legacy urllib.request.urlretrieve API now properly supplies a constant non-zero block_size as it did in Python 3.2 and 2.7. This matches the behavior of urllib.request.URLopener.retrieve.
• Issue #16431: Use the type information when constructing a Decimal subtype from a Decimal argument.
• Issue #15641: Clean up deprecated classes from importlib Patch by Taras Lyapun.
• Issue #16350: zlib.decompressobj().decompress() now accumulates data from successive calls after EOF in unused_data, instead of only saving the argument to the last call. decompressobj().flush() now correctly sets unused_data and unconsumed_tail. A bug in the handling of MemoryError when setting the unconsumed_tail attribute has also been fixed. Patch by Serhiy Storchaka.
• Issue #12759: sre_parse now raises a proper error when the name of the group is missing. Initial patch by Serhiy Storchaka.
• Issue #16152: fix tokenize to ignore whitespace at the end of the code when no newline is found. Patch by Ned Batchelder.
• Issue #16284: Prevent keeping unnecessary references to worker functions in concurrent.futures ThreadPoolExecutor.
• Issue #16230: Fix a crash in select.select() when one the lists changes size while iterated on. Patch by Serhiy Storchaka.
• Issue #16228: Fix a crash in the json module where a list changes size while it is being encoded. Patch by Serhiy Storchaka.
• Issue #16351: New function gc.get_stats() returns per-generation collection statistics.
• Issue #14897: Enhance error messages of struct.pack and struct.pack_into. Patch by Matti Mäki.
• Issue #16316: mimetypes now recognizes the .xz and .txz (.tar.xz) extensions. Patch by Serhiy Storchaka.
• Issue #12890: cgitb no longer prints spurious <p> tags in text mode when the logdir option is specified.
• Issue #16307: Fix multiprocessing.Pool.map_async not calling its callbacks. Patch by Janne Karila.
• Issue #16305: Fix a segmentation fault occurring when interrupting math.factorial.
• Issue #16116: Fix include and library paths to be correct when building C extensions in venvs.
• Issue #16245: Fix the value of a few entities in html.entities.html5.
• Issue #16301: Fix the localhost verification in urllib/request.py for file:// urls.
• Issue #16250: Fix the invocations of URLError which had misplaced filename attribute for exception.
• Issue #10836: Fix exception raised when file not found in urlretrieve Initial patch by Ezio Melotti.
• Issue #14398: Fix size truncation and overflow bugs in the bz2 module.
• Issue #12692: Fix resource leak in urllib.request when talking to an HTTP server that does not include a Connection: close header in its responses.
• Issue #12034: Fix bogus caching of result in check_GetFinalPathNameByHandle. Patch by Atsuo Ishimoto.
• Improve performance of lzma.LZMAFile (see also issue #16034).
• Issue #16220: wsgiref now always calls close() on an iterable response. Patch by Brent Tubbs.
• Issue #16270: urllib may hang when used for retrieving files via FTP by using a context manager. Patch by Giampaolo Rodola’.
• Issue #16461: Wave library should be able to deal with 4GB wav files, and sample rate of 44100 Hz.
• Issue #16176: Properly identify Windows 8 via platform.platform()
• Issue #16088: BaseHTTPRequestHandler’s send_error method includes a Content-Length header in it’s response now. Patch by Antoine Pitrou.
• Issue #16114: The subprocess module no longer provides a misleading error message stating that args[0] did not exist when either the cwd or executable keyword arguments specified a path that did not exist.
• Issue #16169: Fix ctypes.WinError()’s confusion between errno and winerror.
• Issue #16110: logging.fileConfig now accepts a pre-initialised ConfigParser instance.
• Issue #1492704: shutil.copyfile() raises a distinct SameFileError now if source and destination are the same file. Patch by Atsuo Ishimoto.
• Issue #13896: Make shelf instances work with ‘with’ as context managers. Original patch by Filip Gruszczyński.
• Issue #15417: Add support for csh and fish in venv activation scripts.
• Issue #14377: ElementTree.write and some of the module-level functions have a new parameter - short_empty_elements. It controls how elements with no contents are emitted.
• Issue #16089: Allow ElementTree.TreeBuilder to work again with a non-Element element_factory (fixes a regression in SimpleTAL).
• Issue #9650: List commonly used format codes in time.strftime and time.strptime docsttings. Original patch by Mike Hoy.
• Issue #15452: logging configuration socket listener now has a verify option that allows an application to apply a verification function to the received configuration data before it is acted upon.
• Issue #16034: Fix performance regressions in the new bz2.BZ2File implementation. Initial patch by Serhiy Storchaka.
• pty.spawn() now returns the child process status returned by os.waitpid().
• Issue #15756: subprocess.poll() now properly handles errno.ECHILD to return a returncode of 0 when the child has already exited or cannot be waited on.
• Issue #15323: Improve failure message of Mock.assert_called_once_with().
• Issue #16064: unittest -m claims executable is “python”, not “python3”.
• Issue #12376: Pass on parameters in TextTestResult.__init__() super call.
• Issue #15222: Insert blank line after each message in mbox mailboxes.
• Issue #16013: Fix csv.Reader parsing issue with ending quote characters. Patch by Serhiy Storchaka.
• Issue #15421: Fix an OverflowError in Calendar.itermonthdates() after datetime.MAXYEAR. Patch by Cédric Krier.
• Issue #16112: platform.architecture does not correctly escape argument to /usr/bin/file. Patch by David Benjamin.
• Issue #15970: xml.etree.ElementTree now serializes correctly the empty HTML elements ‘meta’ and ‘param’.
• Issue #15842: The SocketIO.{readable,writable,seekable} methods now raise ValueError when the file-like object is closed. Patch by Alessandro Moura.
• Issue #15876: Fix a refleak in the curses module: window.encoding.
• Issue #15881: Fix atexit hook in multiprocessing. Original patch by Chris McDonough.
• Issue #15841: The readable(), writable() and seekable() methods of io.BytesIO and io.StringIO objects now raise ValueError when the object has been closed. Patch by Alessandro Moura.
• Issue #15447: Use subprocess.DEVNULL in webbrowser, instead of opening os.devnull explicitly and leaving it open.
• Issue #15509: webbrowser.UnixBrowser no longer passes empty arguments to Popen when %action substitutions produce empty strings.
• Issue #12776, issue #11839: Call argparse type function (specified by add_argument) only once. Before, the type function was called twice in the case where the default was specified and the argument was given as well. This was especially problematic for the FileType type, as a default file would always be opened, even if a file argument was specified on the command line.
• Issue #15906: Fix a regression in argparse caused by the preceding change, when action='append', type='str' and default=[].
• Issue #16113: Added sha3 module based on the Keccak reference implementation 3.2. The hashlib module has four additional hash algorithms: sha3_224, sha3_256, sha3_384 and sha3_512. As part of the patch some common code was moved from _hashopenssl.c to hashlib.h.
• ctypes.call_commethod was removed, since its only usage was in the defunct samples directory.
• Issue #16692: Added TLSv1.1 and TLSv1.2 support for the ssl modules.
• Issue #16832: add abc.get_cache_token() to expose cache validity checking support in ABCMeta.

IDLE

• Issue #18429: Format / Format Paragraph, now works when comment blocks are selected. As with text blocks, this works best when the selection only includes complete lines.
• Issue #18226: Add docstrings and unittests for FormatParagraph.py. Original patches by Todd Rovito and Phil Webster.
• Issue #18279: Format - Strip trailing whitespace no longer marks a file as changed when it has not been changed. This fix followed the addition of a test file originally written by Phil Webster (the issue’s main goal).
• Issue #7136: In the Idle File menu, “New Window” is renamed “New File”. Patch by Tal Einat, Roget Serwy, and Todd Rovito.
• Remove dead imports of imp.
• Issue #18196: Avoid displaying spurious SystemExit tracebacks.
• Issue #5492: Avoid traceback when exiting IDLE caused by a race condition.
• Issue #17511: Keep IDLE find dialog open after clicking “Find Next”. Original patch by Sarah K.
• Issue #18055: Move IDLE off of imp and on to importlib.
• Issue #15392: Create a unittest framework for IDLE. Initial patch by Rajagopalasarma Jayakrishnan. See Lib/idlelib/idle_test/README.txt for how to run Idle tests.
• Issue #14146: Highlight source line while debugging on Windows.
• Issue #17838: Allow sys.stdin to be reassigned.
• Issue #13495: Avoid loading the color delegator twice in IDLE.
• Issue #17798: Allow IDLE to edit new files when specified on command line.
• Issue #14735: Update IDLE docs to omit “Control-z on Windows”.
• Issue #17532: Always include Options menu for IDLE on OS X. Patch by Guilherme Simões.
• Issue #17585: Fixed IDLE regression. Now closes when using exit() or quit().
• Issue #17657: Show full Tk version in IDLE’s about dialog. Patch by Todd Rovito.
• Issue #17613: Prevent traceback when removing syntax colorizer in IDLE.
• Issue #1207589: Backwards-compatibility patch for right-click menu in IDLE.
• Issue #16887: IDLE now accepts Cancel in tabify/untabify dialog box.
• Issue #17625: In IDLE, close the replace dialog after it is used.
• Issue #14254: IDLE now handles readline correctly across shell restarts.
• Issue #17614: IDLE no longer raises exception when quickly closing a file.
• Issue #6698: IDLE now opens just an editor window when configured to do so.
• Issue #8900: Using keyboard shortcuts in IDLE to open a file no longer raises an exception.
• Issue #6649: Fixed missing exit status in IDLE. Patch by Guilherme Polo.
• Issue #17114: IDLE now uses non-strict config parser.
• Issue #9290: In IDLE the sys.std* streams now implement io.TextIOBase interface and support all mandatory methods and properties.
• Issue #5066: Update IDLE docs. Patch by Todd Rovito.
• Issue #16829: IDLE printing no longer fails if there are spaces or other special characters in the file path.
• Issue #16491: IDLE now prints chained exception tracebacks.
• Issue #16819: IDLE method completion now correctly works for bytes literals.
• Issue #16504: IDLE now catches SyntaxErrors raised by tokenizer. Patch by Roger Serwy.
• Issue #16511: Use default IDLE width and height if config param is not valid. Patch Serhiy Storchaka.
• Issue #1207589: Add Cut/Copy/Paste items to IDLE right click Context Menu Patch by Todd Rovito.
• Issue #16123: IDLE - deprecate running without a subprocess. Patch by Roger Serwy.

Tests

• Issue #1666318: Add a test that shutil.copytree() retains directory permissions. Patch by Catherine Devlin.
• Issue #18273: move the tests in Lib/test/json_tests to Lib/test/test_json and make them discoverable by unittest. Patch by Zachary Ware.
• Fix a fcntl test case on KFreeBSD, Debian #708653 (Petr Salinger).
• Issue #18396: Fix spurious test failure in test_signal on Windows when faulthandler is enabled (Patch by Jeremy Kloth)
• Issue #17046: Fix broken test_executable_without_cwd in test_subprocess.
• Issue #15415: Add new temp_dir() and change_cwd() context managers to test.support, and refactor temp_cwd() to use them. Patch by Chris Jerdonek.
• Issue #15494: test.support is now a package rather than a module (Initial patch by Indra Talip)
• Issue #17944: test_zipfile now discoverable and uses subclassing to generate tests for different compression types. Fixed a bug with skipping some tests due to use of exhausted iterators.
• Issue #18266: test_largefile now works with unittest test discovery and supports running only selected tests. Patch by Zachary Ware.
• Issue #17767: test_locale now works with unittest test discovery. Original patch by Zachary Ware.
• Issue #18375: Assume –randomize when –randseed is used for running the testsuite.
• Issue #11185: Fix test_wait4 under AIX. Patch by Sébastien Sablé.
• Issue #18207: Fix test_ssl for some versions of OpenSSL that ignore seconds in ASN1_TIME fields.
• Issue #18094: test_uuid no longer reports skipped tests as passed.
• Issue #17992: Add timeouts to asyncore and asynchat tests so that they won’t accidentally hang.
• Issue #17833: Fix test_gdb failures seen on machines where debug symbols for glibc are available (seen on PPC64 Linux).
• Issue #7855: Add tests for ctypes/winreg for issues found in IronPython. Initial patch by Dino Viehland.
• Issue #11078: test___all__ now checks for duplicates in __all__. Initial patch by R. David Murray.
• Issue #17712: Fix test_gdb failures on Ubuntu 13.04.
• Issue #17835: Fix test_io when the default OS pipe buffer size is larger than one million bytes.
• Issue #17065: Use process-unique key for winreg tests to avoid failures if test is run multiple times in parallel (eg: on a buildbot host).
• Issue #12820: add tests for the xml.dom.minicompat module. Patch by John Chandler and Phil Connell.
• Issue #17691: test_univnewlines now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17790: test_set now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17789: test_random now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17779: test_osx_env now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17766: test_iterlen now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17690: test_time now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17692: test_sqlite now works with unittest test discovery. Patch by Zachary Ware.
• Issue #11995: test_pydoc doesn’t import all sys.path modules anymore.
• Issue #17448: test_sax now skips if there are no xml parsers available instead of raising an ImportError.
• Issue #11420: make test suite pass with -B/DONTWRITEBYTECODE set. Initial patch by Thomas Wouters.
• Issue #10652: make tcl/tk tests run after __all__ test, patch by Zachary Ware.
• Issue #11963: remove human verification from test_parser and test_subprocess.
• Issue #11732: add a new suppress_crash_popup() context manager to test.support that disables crash popups on Windows and use it in test_faulthandler and test_capi.
• Issue #13898: test_ssl no longer prints a spurious stack trace on Ubuntu.
• Issue #17283: Share code between __main__.py and regrtest.py in Lib/test.
• Issue #17249: convert a test in test_capi to use unittest and reap threads.
• Issue #17107: Test client-side SNI support in urllib.request thanks to the new server-side SNI support in the ssl module. Initial patch by Daniel Black.
• Issue #17041: Fix testing when Python is configured with the –without-doc-strings.
• Issue #16923: Fix ResourceWarnings in test_ssl.
• Issue #15539: Added regression tests for Tools/scripts/pindent.py.
• Issue #17479: test_io now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17066: test_robotparser now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17334: test_index now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17333: test_imaplib now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17082: test_dbm* now work with unittest test discovery. Patch by Zachary Ware.
• Issue #17079: test_ctypes now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17304: test_hash now works with unittest test discovery. Patch by Zachary Ware.
• Issue #17303: test_future* now work with unittest test discovery. Patch by Zachary Ware.
• Issue #17163: test_file now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16925: test_configparser now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16918: test_codecs now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16919: test_crypt now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16910: test_bytes, test_unicode, and test_userstring now work with unittest test discovery. Patch by Zachary Ware.
• Issue #16905: test_warnings now works with unittest test discovery. Initial patch by Berker Peksag.
• Issue #16898: test_bufio now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16888: test_array now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16896: test_asyncore now works with unittest test discovery. Patch by Zachary Ware.
• Issue #16897: test_bisect now works with unittest test discovery. Initial patch by Zachary Ware.
• Issue #16852: test_genericpath, test_posixpath, test_ntpath, and test_macpath now work with unittest test discovery. Patch by Zachary Ware.
• Issue #16748: test_heapq now works with unittest test discovery.
• Issue #10646: Tests rearranged for os.samefile/samestat to check for not just symlinks but also hard links.
• Issue #15302: Switch regrtest from using getopt to using argparse.
• Issue #15324: Fix regrtest parsing of –fromfile, –match, and –randomize options.
• Issue #16702: test_urllib2_localnet tests now correctly ignores proxies for localhost tests.
• Issue #16664: Add regression tests for glob’s behaviour concerning entries starting with a ”.”. Patch by Sebastian Kreft.
• Issue #13390: The -R option to regrtest now also checks for memory allocation leaks, using sys.getallocatedblocks().
• Issue #16559: Add more tests for the json module, including some from the official test suite at json.org. Patch by Serhiy Storchaka.
• Issue #16661: Fix the os.getgrouplist() test by not assuming that it gives the same output as id -G.
• Issue #16115: Add some tests for the executable argument to subprocess.Popen(). Initial patch by Kushal Das.
• Issue #16126: PyErr_Format format mismatch in _testcapimodule.c. Patch by Serhiy Storchaka.
• Issue #15304: Fix warning message when os.chdir() fails inside test.support.temp_cwd(). Patch by Chris Jerdonek.
• Issue #15802: Fix test logic in TestMaildir.test_create_tmp(). Patch by Serhiy Storchaka.
• Issue #15557: Added a test suite for the webbrowser module, thanks to Anton Barkovsky.
• Issue #16698: Skip posix test_getgroups when built with OS X deployment target prior to 10.6.

Build

• Issue #16067: Add description into MSI file to replace installer’s temporary name.
• Issue #18257: Fix readlink usage in python-config. Install the python version again on Darwin.
• Issue #18481: Add C coverage reporting with gcov and lcov. A new make target “coverage-report” creates an instrumented Python build, runs unit tests and creates a HTML. The report can be updated with “make coverage-lcov”.
• Issue #17845: Clarified the message printed when some module are not built.
• Issue #18256: Compilation fix for recent AIX releases. Patch by David Edelsohn.
• Issue #17547: In configure, explicitly pass -Wformat for the benefit for GCC 4.8.
• Issue #15172: Document NASM 2.10+ as requirement for building OpenSSL 1.0.1 on Windows.
• Issue #17591: Use lowercase filenames when including Windows header files. Patch by Roumen Petrov.
• Issue #17550: Fix the –enable-profiling configure switch.
• Issue #17425: Build with openssl 1.0.1d on Windows.
• Issue #16754: Fix the incorrect shared library extension on linux. Introduce two makefile macros SHLIB_SUFFIX and EXT_SUFFIX. SO now has the value of SHLIB_SUFFIX again (as in 2.x and 3.1). The SO macro is removed in 3.4.
• Issue #5033: Fix building of the sqlite3 extension module when the SQLite library version has “beta” in it. Patch by Andreas Pelme.
• Issue #17228: Fix building without pymalloc.
• Issue #3718: Use AC_ARG_VAR to set MACHDEP in configure.ac.
• Issue #16235: Implement python-config as a shell script.
• Issue #16769: Remove outdated Visual Studio projects.
• Issue #17031: Fix running regen in cross builds.
• Issue #3754: fix typo in pthread AC_CACHE_VAL.
• Issue #15484: Fix _PYTHON_PROJECT_BASE for srcdir != builddir builds; use _PYTHON_PROJECT_BASE in distutils/sysconfig.py.
• Drop support for Windows 2000 (changeset e52df05b496a).
• Issue #17029: Let h2py search the multiarch system include directory.
• Issue #16953: Fix socket module compilation on platforms with HAVE_BROKEN_POLL. Patch by Jeffrey Armstrong.
• Issue #16320: Remove redundant Makefile dependencies for strings and bytes.
• Cross compiling needs host and build settings. configure no longer creates a broken PYTHON_FOR_BUILD variable when –build is missing.
• Fix cross compiling issue in setup.py, ensure that lib_dirs and inc_dirs are defined in cross compiling mode, too.
• Issue #16836: Enable IPv6 support even if IPv6 is disabled on the build host.
• Issue #16593: Have BSD ‘make -s’ do the right thing, thanks to Daniel Shahaf
• Issue #16262: fix out-of-src-tree builds, if mercurial is not installed.
• Issue #15298: ensure _sysconfigdata is generated in build directory, not source directory.
• Issue #15833: Fix a regression in 3.3 that resulted in exceptions being raised if importlib failed to write byte-compiled files. This affected attempts to build Python out-of-tree from a read-only source directory.
• Issue #15923: Fix a mistake in asdl_c.py that resulted in a TypeError after 2801bf875a24 (see #15801).
• Issue #16135: Remove OS/2 support.
• Issue #15819: Make sure we can build Python out-of-tree from a read-only source directory. (Somewhat related to issue #9860.)
• Issue #15587: Enable Tk high-resolution text rendering on Macs with Retina displays. Applies to Tkinter apps, such as IDLE, on OS X framework builds linked with Cocoa Tk 8.5.
• Issue #17161: make install now also installs a python3 man page.

C-API

• Issue #18351: Fix various issues in a function in importlib provided to help PyImport_ExecCodeModuleWithPathnames() (and thus by extension PyImport_ExecCodeModule() and PyImport_ExecCodeModuleEx()).
• Issue #9369: The types of char* arguments of PyObject_CallFunction() and PyObject_CallMethod() now changed to const char*. Based on patches by Jörg Müller and Lars Buitinck.
• Issue #17206: Py_CLEAR(), Py_DECREF(), Py_XINCREF() and Py_XDECREF() now expand their arguments once instead of multiple times. Patch written by Illia Polosukhin.
• Issue #17522: Add the PyGILState_Check() API.
• Issue #17327: Add PyDict_SetDefault.
• Issue #16881: Fix Py_ARRAY_LENGTH macro for GCC < 3.1.
• Issue #16505: Remove unused Py_TPFLAGS_INT_SUBCLASS.
• Issue #16086: PyTypeObject.tp_flags and PyType_Spec.flags are now unsigned (unsigned long and unsigned int) to avoid an undefined behaviour with Py_TPFLAGS_TYPE_SUBCLASS ((1 << 31). PyType_GetFlags() result type is now unsigned too (unsigned long, instead of long).
• Issue #16166: Add PY_LITTLE_ENDIAN and PY_BIG_ENDIAN macros and unified endianness detection and handling.

Documentation

• Issue #23006: Improve the documentation and indexing of dict.__missing__. Add an entry in the language datamodel special methods section. Revise and index its discussion in the stdtypes mapping/dict section.
• Issue #17701: Improving strftime documentation.
• Issue #18440: Clarify that hash() can truncate the value returned from an object’s custom __hash__() method.
• Issue #17844: Add links to encoders and decoders for bytes-to-bytes codecs.
• Issue #14097: improve the “introduction” page of the tutorial.
• Issue #17977: The documentation for the cadefault argument’s default value in urllib.request.urlopen() is fixed to match the code.
• Issue #6696: add documentation for the Profile objects, and improve profile/cProfile docs. Patch by Tom Pinckney.
• Issue #15940: Specify effect of locale on time functions.
• Issue #17538: Document XML vulnerabilties
• Issue #16642: sched.scheduler timefunc initial default is time.monotonic. Patch by Ramchandra Apte
• Issue #17047: remove doubled words in docs and docstrings reported by Serhiy Storchaka and Matthew Barnett.
• Issue #15465: Document the versioning macros in the C API docs rather than the standard library docs. Patch by Kushal Das.
• Issue #16406: Combine the pages for uploading and registering to PyPI.
• Issue #16403: Document how distutils uses the maintainer field in PKG-INFO. Patch by Jyrki Pulliainen.
• Issue #16695: Document how glob handles filenames starting with a dot. Initial patch by Jyrki Pulliainen.
• Issue #8890: Stop advertising an insecure practice by replacing uses of the /tmp directory with better alternatives in the documentation. Patch by Geoff Wilson.
• Issue #17203: add long option names to unittest discovery docs.
• Issue #13094: add “Why do lambdas defined in a loop with different values all return the same result?” programming FAQ.
• Issue #14901: Update portions of the Windows FAQ. Patch by Ashish Nitin Patil.
• Issue #16267: Better document the 3.3+ approach to combining @abstractmethod with @staticmethod, @classmethod and @property
• Issue #15209: Clarify exception chaining description in exceptions module documentation
• Issue #15990: Improve argument/parameter documentation.
• Issue #16209: Move the documentation for the str built-in function to a new str class entry in the “Text Sequence Type” section.
• Issue #13538: Improve str() and object.__str__() documentation.
• Issue #16489: Make it clearer that importlib.find_loader() needs parent packages to be explicitly imported.
• Issue #16400: Update the description of which versions of a given package PyPI displays.
• Issue #15677: Document that zlib and gzip accept a compression level of 0 to mean ‘no compression’. Patch by Brian Brazil.
• Issue #16197: Update winreg docstrings and documentation to match code. Patch by Zachary Ware.
• Issue #8040: added a version switcher to the documentation. Patch by Yury Selivanov.
• Issue #16241: Document -X faulthandler command line option. Patch by Marek Šuppa.
• Additional comments and some style changes in the concurrent.futures URL retrieval example
• Issue #16115: Improve subprocess.Popen() documentation around args, shell, and executable arguments.
• Issue #13498: Clarify docs of os.makedirs()’s exist_ok argument. Done with great native-speaker help from R. David Murray.
• Issue #15533: Clarify docs and add tests for subprocess.Popen()‘s cwd argument.
• Issue #15979: Improve timeit documentation.
• Issue #16036: Improve documentation of built-in int()‘s signature and arguments.
• Issue #15935: Clarification of argparse docs, re: add_argument() type and default arguments. Patch contributed by Chris Jerdonek.
• Issue #11964: Document a change in v3.2 to the behavior of the indent parameter of json encoding operations.
• Issue #15116: Remove references to appscript as it is no longer being supported.

Tools/Demos

• Issue #18817: Fix a resource warning in Lib/aifc.py demo. Patch by Vajrasky Kok.
• Issue #18439: Make patchcheck work on Windows for ACKS, NEWS.
• Issue #18448: Fix a typo in Tools/demo/eiffel.py.
• Issue #18457: Fixed saving of formulas and complex numbers in Tools/demo/ss1.py.
• Issue #18449: Make Tools/demo/ss1.py work again on Python 3. Patch by Févry Thibault.
• Issue #12990: The “Python Launcher” on OSX could not launch python scripts that have paths that include wide characters.
• Issue #15239: Make mkstringprep.py work again on Python 3.
• Issue #17028: Allowed Python arguments to be supplied to the Windows launcher.
• Issue #17156: pygettext.py now detects the encoding of source files and correctly writes and escapes non-ascii characters.
• Issue #15539: Fix a number of bugs in Tools/scripts/pindent.py. Now pindent.py works with a “with” statement. pindent.py no longer produces improper indentation. pindent.py now works with continued lines broken after “class” or “def” keywords and with continuations at the start of line.
• Issue #11797: Add a 2to3 fixer that maps reload() to imp.reload().
• Issue #10966: Remove the concept of unexpected skipped tests.
• Issue #9893: Removed the Misc/Vim directory.
• Removed the Misc/TextMate directory.
• Issue #16245: Add the Tools/scripts/parse_html5_entities.py script to parse the list of HTML5 entities and update the html.entities.html5 dictionary.
• Issue #15378: Fix Tools/unicode/comparecodecs.py. Patch by Serhiy Storchaka.
• Issue #16549: Make json.tool work again on Python 3 and add tests. Initial patch by Berker Peksag and Serhiy Storchaka.
• Issue #13301: use ast.literal_eval() instead of eval() in Tools/i18n/msgfmt.py Patch by Serhiy Storchaka.

Windows

• Issue #18569: The installer now adds .py to the PATHEXT variable when extensions are registered. Patch by Paul Moore.

(For information about older versions, consult the HISTORY file.)