• Setting sys.tracebacklimit to 0 or less now suppresses printing tracebacks.
• Setting sys.tracebacklimit to None now causes using the default limit.
• Setting sys.tracebacklimit to an integer larger than LONG_MAX now means using the limit LONG_MAX rather than the default limit.
• Fixed integer overflows in the case of more than 2**31 traceback items on Windows.
• Fixed output errors handling.

bpo-28556: Two minor fixes for typing module: allow shallow copying instances of generic classes, improve interaction of __init_subclass__ with generics. Original PRs by Ivan Levkivskyi.

bpo-27240: The header folding algorithm for the new email policies has been rewritten, which also fixes bpo-30788, bpo-31831, and bpo-32182. In particular, RFC2231 folding is now done correctly.

bpo-32186: io.FileIO.readall() and io.FileIO.read() now release the GIL when getting the file size. Fixed hang of all threads with inaccessible NFS server. Patch by Nir Soffer.

bpo-12239: Make msilib.SummaryInformation.GetProperty() return None when the value of property is VT_EMPTY. Initial patch by Mark Mc Mahon.

bpo-31325: Fix wrong usage of collections.namedtuple() in the RobotFileParser.parse() method.

Initial patch by Robin Wellner.

bpo-12382: msilib.OpenDatabase() now raises a better exception message when it couldn’t open or create an MSI file. Initial patch by William Tisäter.

bpo-32110: codecs.StreamReader.read(n) now returns not more than n characters/bytes for non-negative n. This makes it compatible with read() methods of other file-like objects.

bpo-32072: Fixed issues with binary plists:

• Fixed saving bytearrays.
• Identical objects will be saved only once.
• Equal references will be load as identical objects.
• Added support for saving and loading recursive data structures.

bpo-32034: Make asyncio.IncompleteReadError and LimitOverrunError pickleable.

bpo-32015: Fixed the looping of asyncio in the case of reconnection the socket during waiting async read/write from/to the socket.

bpo-32011: Restored support of loading marshal files with the TYPE_INT64 code. These files can be produced in Python 2.7.

bpo-31970: Reduce performance overhead of asyncio debug mode.

bpo-9678: Fixed determining the MAC address in the uuid module:

• Using ifconfig on NetBSD and OpenBSD.
• Using arp on Linux, FreeBSD, NetBSD and OpenBSD.

Based on patch by Takayuki Shimizukawa.

bpo-30057: Fix potential missed signal in signal.signal().

bpo-31933: Fix Blake2 params leaf_size and node_offset on big endian platforms. Patch by Jack O’Connor.

bpo-31927: Fixed compilation of the socket module on NetBSD 8. Fixed assertion failure or reading arbitrary data when parse a AF_BLUETOOTH address on NetBSD and DragonFly BSD.

bpo-27666: Fixed stack corruption in curses.box() and curses.ungetmouse() when the size of types chtype or mmask_t is less than the size of C long. curses.box() now accepts characters as arguments. Based on patch by Steve Fink.

bpo-31897: plistlib now catches more errors when read binary plists and raises InvalidFileException instead of unexpected exceptions.

bpo-25720: Fix the method for checking pad state of curses WINDOW. Patch by Masayuki Yamamoto.

bpo-31893: Fixed the layout of the kqueue_event structure on OpenBSD and NetBSD. Fixed the comparison of the kqueue_event objects.

bpo-31891: Fixed building the curses module on NetBSD.

bpo-28416: Instances of pickle.Pickler subclass with the persistent_id() method and pickle.Unpickler subclass with the persistent_load() method no longer create reference cycles.

bpo-28326: Fix multiprocessing.Process when stdout and/or stderr is closed or None.

bpo-31457: If nested log adapters are used, the inner process() methods are no longer omitted.

bpo-31457: The manager property on LoggerAdapter objects is now properly settable.

bpo-31806: Fix timeout rounding in time.sleep(), threading.Lock.acquire() and socket.socket.settimeout() to round correctly negative timeouts between -1.0 and 0.0. The functions now block waiting for events as expected. Previously, the call was incorrectly non-blocking. Patch by Pablo Galindo.

bpo-28603: traceback: Fix a TypeError that occurred during printing of exception tracebacks when either the current exception or an exception in its context/cause chain is unhashable. Patch by Zane Bitter.

bpo-30058: Fixed buffer overflow in select.kqueue.control().

bpo-31770: Prevent a crash when calling the __init__() method of a sqlite3.Cursor object more than once. Patch by Oren Milman.

bpo-31672: idpattern in string.Template matched some non-ASCII characters. Now it uses -i regular expression local flag to avoid non- ASCII characters.

bpo-31764: Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized. Patch by Oren Milman.

bpo-31752: Fix possible crash in timedelta constructor called with custom integers.

bpo-31701: On Windows, faulthandler.enable() now ignores MSC and COM exceptions.

bpo-31728: Prevent crashes in _elementtree due to unsafe cleanup of Element.text and Element.tail. Patch by Oren Milman.

bpo-31620: an empty asyncio.Queue now doesn’t leak memory when queue.get pollers timeout

bpo-31632: Fix method set_protocol() of class _SSLProtocolTransport in asyncio module. This method was previously modifying a wrong reference to the protocol.

bpo-31675: Fixed memory leaks in Tkinter’s methods splitlist() and split() when pass a string larger than 2 GiB.

bpo-31673: Fixed typo in the name of Tkinter’s method adderrorinfo().

bpo-30806: Fix the string representation of a netrc object.

bpo-15037: Added a workaround for getkey() in curses for ncurses 5.7 and earlier.

bpo-25351: Avoid venv activate failures with undefined variables

bpo-25532: inspect.unwrap() will now only try to unwrap an object sys.getrecursionlimit() times, to protect against objects which create a new object on every attribute access.

bpo-30347: Stop crashes when concurrently iterate over itertools.groupby() iterators.

bpo-31516: threading.current_thread() should not return a dummy thread at shutdown.

bpo-31351: python -m ensurepip now exits with non-zero exit code if pip bootstrapping has failed.

bpo-31482: random.seed() now works with bytes in version=1

bpo-31334: Fix poll.poll([timeout]) in the select module for arbitrary negative timeouts on all OSes where it can only be a non- negative integer or -1. Patch by Riccardo Coccioli.

bpo-31310: multiprocessing’s semaphore tracker should be launched again if crashed.

bpo-31308: Make multiprocessing’s forkserver process immune to Ctrl-C and other user interruptions. If it crashes, restart it when necessary.

bpo-1102: Return None when View.Fetch() returns ERROR_NO_MORE_ITEMS instead of raising MSIError.

Initial patch by Anthony Tuininga.

bpo-31944: Fixes Modify button in Apps and Features dialog.

bpo-32207: Improve tk event exception tracebacks in IDLE. When tk event handling is driven by IDLE’s run loop, a confusing and distracting queue.EMPTY traceback context is no longer added to tk event exception tracebacks. The traceback is now the same as when event handling is driven by user code. Patch based on a suggestion by Serhiy Storchaka.

bpo-32164: Delete unused file idlelib/tabbedpages.py. Use of TabbedPageSet in configdialog was replaced by ttk.Notebook.

bpo-32100: IDLE: Fix old and new bugs in pathbrowser; improve tests. Patch mostly by Cheryl Sabella.

bpo-31858: IDLE – Restrict shell prompt manipulaton to the shell. Editor and output windows only see an empty last prompt line. This simplifies the code and fixes a minor bug when newline is inserted. Sys.ps1, if present, is read on Shell start-up, but is not set or changed.

bpo-31860: The font sample in the IDLE configuration dialog is now editable. Changes persist while IDLE remains open

bpo-31836: Test_code_module now passes if run after test_idle, which sets ps1.

The code module uses sys.ps1 if present or sets it to ‘>>> ‘ if not. Test_code_module now properly tests both behaviors. Ditto for ps2.

bpo-28603: Fix a TypeError that caused a shell restart when printing a traceback that includes an exception that is unhashable. Patch by Zane Bitter.

bpo-13802: Use non-Latin characters in the IDLE’s Font settings sample. Even if one selects a font that defines a limited subset of the unicode Basic Multilingual Plane, tcl/tk will use other fonts that define a character. The expanded example give users of non-Latin characters a better idea of what they might see in IDLE’s shell and editors. To make room for the expanded sample, frames on the Font tab are re-arranged. The Font/Tabs help explains a bit about the additions.

bpo-31460: Simplify the API of IDLE’s Module Browser.

Passing a widget instead of an flist with a root widget opens the option of creating a browser frame that is only part of a window. Passing a full file name instead of pieces assumed to come from a .py file opens the possibility of browsing python files that do not end in .py.

bpo-31649: IDLE - Make _htest, _utest parameters keyword only.

bpo-31559: Remove test order dependence in idle_test.test_browser.

bpo-31459: Rename IDLE’s module browser from Class Browser to Module Browser. The original module-level class and method browser became a module browser, with the addition of module-level functions, years ago. Nested classes and functions were added yesterday. For back- compatibility, the virtual event <<open-class-browser>>, which appears on the Keys tab of the Settings dialog, is not changed. Patch by Cheryl Sabella.

bpo-31500: Default fonts now are scaled on HiDPI displays.

bpo-1612262: IDLE module browser now shows nested classes and functions. Original patches for code and tests by Guilherme Polo and Cheryl Sabella, respectively.

bpo-30722: Make redemo work with Python 3.6 and newer versions.

In Python 3.6, flags like re.DOTALL became members of an enum.IntFlag so usages like getattr(re, 'DOTALL') are invalid.

Also, remove the LOCALE option since it doesn’t work with string patterns in Python 3.

Patch by Christoph Sarnowski.

bpo-31471: Fix an assertion failure in subprocess.Popen() on Windows, in case the env argument has a bad keys() method. Patch by Oren Milman.

bpo-31418: Fix an assertion failure in PyErr_WriteUnraisable() in case of an exception with a bad __module__ attribute. Patch by Oren Milman.

bpo-31416: Fix assertion failures in case of a bad warnings.filters or warnings.defaultaction. Patch by Oren Milman.

bpo-31411: Raise a TypeError instead of SystemError in case warnings.onceregistry is not a dictionary. Patch by Oren Milman.

bpo-31373: Fix several possible instances of undefined behavior due to floating-point demotions.

bpo-30465: Location information (lineno and col_offset) in f-strings is now (mostly) correct. This fixes tools like flake8 from showing warnings on the wrong line (typically the first line of the file).

bpo-31343: Include sys/sysmacros.h for major(), minor(), and makedev(). GNU C libray plans to remove the functions from sys/types.h.

bpo-31291: Fix an assertion failure in zipimport.zipimporter.get_data on Windows, when the return value of pathname.replace('/','\\') isn’t a string. Patch by Oren Milman.

bpo-31271: Fix an assertion failure in the write() method of io.TextIOWrapper, when the encoder doesn’t return a bytes object. Patch by Oren Milman.

bpo-31243: Fix a crash in some methods of io.TextIOWrapper, when the decoder’s state is invalid. Patch by Oren Milman.

bpo-30721: print now shows correct usage hint for using Python 2 redirection syntax. Patch by Sanyam Khurana.

bpo-31070: Fix a race condition in importlib _get_module_lock().

bpo-31095: Fix potential crash during GC caused by tp_dealloc which doesn’t call PyObject_GC_UnTrack().

bpo-31071: Avoid masking original TypeError in call with * unpacking when other arguments are passed.

bpo-30978: str.format_map() now passes key lookup exceptions through. Previously any exception was replaced with a KeyError exception.

bpo-30808: Use _Py_atomic API for concurrency-sensitive signal state.

bpo-30876: Relative import from unloaded package now reimports the package instead of failing with SystemError. Relative import from non-package now fails with ImportError rather than SystemError.

bpo-30703: Improve signal delivery.

Avoid using Py_AddPendingCall from signal handler, to avoid calling signal- unsafe functions. The tests I’m adding here fail without the rest of the patch, on Linux and OS X. This means our signal delivery logic had defects (some signals could be lost).

bpo-30765: Avoid blocking in pthread_mutex_lock() when PyThread_acquire_lock() is asked not to block.

bpo-31161: Make sure the ‘Missing parentheses’ syntax error message is only applied to SyntaxError, not to subclasses. Patch by Martijn Pieters.

bpo-30814: Fixed a race condition when import a submodule from a package.

bpo-30597: print now shows expected input in custom error message when used as a Python 2 statement. Patch by Sanyam Khurana.

bpo-31499: xml.etree: Fix a crash when a parser is part of a reference cycle.

bpo-28556: typing.get_type_hints now finds the right globalns for classes and modules by default (when no globalns was specified by the caller).

bpo-28556: Speed improvements to the typing module. Original PRs by Ivan Levkivskyi and Mitar.

bpo-31544: The C accelerator module of ElementTree ignored exceptions raised when looking up TreeBuilder target methods in XMLParser().

bpo-31234: socket.create_connection() now fixes manually a reference cycle: clear the variable storing the last exception on success.

bpo-31457: LoggerAdapter objects can now be nested.

bpo-31400: Improves SSL error handling to avoid losing error numbers.

bpo-28958: ssl.SSLContext() now uses OpenSSL error information when a context cannot be instantiated.

bpo-27340: SSLSocket.sendall() now uses memoryview to create slices of data. This fixes support for all bytes-like object. It is also more efficient and avoids costly copies.

bpo-31178: Fix string concatenation bug in rare error path in the subprocess module

bpo-31350: Micro-optimize asyncio._get_running_loop() to become up to 10% faster.

bpo-31170: expat: Update libexpat from 2.2.3 to 2.2.4. Fix copying of partial characters for UTF-8 input (libexpat bug 115): https://github.com/libexpat/libexpat/issues/115

bpo-29136: Add TLS 1.3 cipher suites and OP_NO_TLSv1_3.

bpo-29212: Fix concurrent.futures.thread.ThreadPoolExecutor threads to have a non repr() based thread name by default when no thread_name_prefix is supplied. They will now identify themselves as “ThreadPoolExecutor- y_n”.

bpo-9146: Fix a segmentation fault in _hashopenssl when standard hash functions such as md5 are not available in the linked OpenSSL library. As in some special FIPS-140 build environments.

bpo-27144: The map() and as_completed() iterators in concurrent.futures now avoid keeping a reference to yielded objects.

bpo-10746: Fix ctypes producing wrong PEP 3118 type codes for integer types.

bpo-22536: The subprocess module now sets the filename when FileNotFoundError is raised on POSIX systems due to the executable or cwd not being found.

bpo-31249: concurrent.futures: WorkItem.run() used by ThreadPoolExecutor now breaks a reference cycle between an exception object and the WorkItem object.

bpo-31247: xmlrpc.server now explicitly breaks reference cycles when using sys.exc_info() in code handling exceptions.

bpo-30102: The ssl and hashlib modules now call OPENSSL_add_all_algorithms_noconf() on OpenSSL < 1.1.0. The function detects CPU features and enables optimizations on some CPU architectures such as POWER8. Patch is based on research from Gustavo Serra Scalet.

bpo-31185: Fixed miscellaneous errors in asyncio speedup module.

bpo-31135: ttk: fix the destroy() method of LabeledScale and OptionMenu classes. Call the parent destroy() method even if the used attribute doesn’t exist. The LabeledScale.destroy() method now also explicitly clears label and scale attributes to help the garbage collector to destroy all widgets.

bpo-31107: Fix copyreg._slotnames() mangled attribute calculation for classes whose name begins with an underscore. Patch by Shane Harvey.

bpo-31061: Fixed a crash when using asyncio and threads.

bpo-30502: Fix handling of long oids in ssl. Based on patch by Christian Heimes.

bpo-30119: ftplib.FTP.putline() now throws ValueError on commands that contains CR or LF. Patch by Dong-hee Na.

bpo-30595: multiprocessing.Queue.get() with a timeout now polls its reader in non- blocking mode if it succeeded to aquire the lock but the acquire took longer than the timeout.

bpo-29403: Fix unittest.mock’s autospec to not fail on method-bound builtin functions. Patch by Aaron Gallagher.

bpo-30961: Fix decrementing a borrowed reference in tracemalloc.

bpo-25684: Change ttk.OptionMenu radiobuttons to be unique across instances of OptionMenu.

bpo-30886: Fix multiprocessing.Queue.join_thread(): it now waits until the thread completes, even if the thread was started by the same process which created the queue.

bpo-29854: Fix segfault in readline when using readline’s history-size option. Patch by Nir Soffer.

bpo-30319: socket.close() now ignores ECONNRESET error.

bpo-30828: Fix out of bounds write in asyncio.CFuture.remove_done_callback().

bpo-30807: signal.setitimer() may disable the timer when passed a tiny value.

Tiny values (such as 1e-6) are valid non-zero values for setitimer(), which is specified as taking microsecond-resolution intervals. However, on some platform, our conversion routine could convert 1e-6 into a zero interval, therefore disabling the timer instead of (re-)scheduling it.

bpo-30441: Fix bug when modifying os.environ while iterating over it

bpo-30532: Fix email header value parser dropping folding white space in certain cases.

bpo-30879: os.listdir() and os.scandir() now emit bytes names when called with bytes- like argument.

bpo-30746: Prohibited the ‘=’ character in environment variable names in os.putenv() and os.spawn*().

bpo-29755: Fixed the lgettext() family of functions in the gettext module. They now always return bytes.

bpo-31493: IDLE code context – fix code update and font update timers.

Canceling timers prevents a warning message when test_idle completes.

bpo-31488: IDLE - Update non-key options in former extension classes. When applying configdialog changes, call .reload for each feature class. Change ParenMatch so updated options affect existing instances attached to existing editor windows.

bpo-31477: IDLE - Improve rstrip entry in doc. Strip trailing whitespace strips more than blank spaces. Multiline string literals are not skipped.

bpo-31480: IDLE - make tests pass with zzdummy extension disabled by default.

bpo-31421: Document how IDLE runs tkinter programs. IDLE calls tcl/tk update in the background in order to make live

interaction and experimentatin with tkinter applications much easier.

bpo-31414: IDLE – fix tk entry box tests by deleting first. Adding to an int entry is not the same as deleting and inserting because int(‘’) will fail.

bpo-31051: Rearrange IDLE condigdialog GenPage into Window, Editor, and Help sections.

bpo-30617: IDLE - Add docstrings and tests for outwin subclass of editor.

Move some data and functions from the class to module level. Patch by Cheryl Sabella.

bpo-31287: IDLE - Do not modify tkinter.message in test_configdialog.

bpo-27099: Convert IDLE’s built-in ‘extensions’ to regular features.

About 10 IDLE features were implemented as supposedly optional extensions. Their different behavior could be confusing or worse for users and not good for maintenance. Hence the conversion.

The main difference for users is that user configurable key bindings for builtin features are now handled uniformly. Now, editing a binding in a keyset only affects its value in the keyset. All bindings are defined together in the system-specific default keysets in config- extensions.def. All custom keysets are saved as a whole in config- extension.cfg. All take effect as soon as one clicks Apply or Ok.

The affected events are ‘<<force-open-completions>>’, ‘<<expand-word>>’, ‘<<force-open-calltip>>’, ‘<<flash-paren>>’, ‘<<format-paragraph>>’, ‘<<run- module>>’, ‘<<check-module>>’, and ‘<<zoom-height>>’. Any (global) customizations made before 3.6.3 will not affect their keyset- specific customization after 3.6.3. and vice versa.

Inital patch by Charles Wohlganger.

bpo-31206: IDLE: Factor HighPage(Frame) class from ConfigDialog. Patch by Cheryl Sabella.

bpo-31001: Add tests for configdialog highlight tab. Patch by Cheryl Sabella.

bpo-31205: IDLE: Factor KeysPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

bpo-31130: IDLE – stop leaks in test_configdialog. Initial patch by Victor Stinner.

bpo-31002: Add tests for configdialog keys tab. Patch by Cheryl Sabella.

bpo-19903: IDLE: Calltips use inspect.signature instead of inspect.getfullargspec. This improves calltips for builtins converted to use Argument Clinic. Patch by Louie Lu.

bpo-31083: IDLE - Add an outline of a TabPage class in configdialog. Update existing classes to match outline. Initial patch by Cheryl Sabella.

bpo-31050: Factor GenPage(Frame) class from ConfigDialog. The slightly modified tests continue to pass. Patch by Cheryl Sabella.

bpo-31004: IDLE - Factor FontPage(Frame) class from ConfigDialog.

Slightly modified tests continue to pass. Fix General tests. Patch mostly by Cheryl Sabella.

bpo-30781: IDLE - Use ttk widgets in ConfigDialog. Patches by Terry Jan Reedy and Cheryl Sabella.

bpo-31060: IDLE - Finish rearranging methods of ConfigDialog Grouping methods pertaining to each tab and the buttons will aid writing tests and improving the tabs and will enable splitting the groups into classes.

bpo-30853: IDLE – Factor a VarTrace class out of ConfigDialog.

Instance tracers manages pairs consisting of a tk variable and a callback function. When tracing is turned on, setting the variable calls the function. Test coverage for the new class is 100%.

bpo-31003: IDLE: Add more tests for General tab.

bpo-30993: IDLE - Improve configdialog font page and tests.

In configdialog: Document causal pathways in create_font_tab docstring. Simplify some attribute names. Move set_samples calls to var_changed_font (idea from Cheryl Sabella). Move related functions to positions after the create widgets function.

In test_configdialog: Fix test_font_set so not order dependent. Fix renamed test_indent_scale so it tests the widget. Adjust tests for movement of set_samples call. Add tests for load functions. Put all font tests in one class and tab indent tests in another. Except for two lines, these tests completely cover the related functions.

bpo-30981: IDLE – Add more configdialog font page tests.

bpo-28523: IDLE: replace ‘colour’ with ‘color’ in configdialog.

bpo-30917: Add tests for idlelib.config.IdleConf. Increase coverage from 46% to 96%. Patch by Louie Lu.

bpo-30934: Document coverage details for idlelib tests.

• Add section to idlelib/idle-test/README.txt.
• Include check that branches are taken both ways.
• Exclude IDLE-specific code that does not run during unit tests.

bpo-30913: IDLE: Document ConfigDialog tk Vars, methods, and widgets in docstrings This will facilitate improving the dialog and splitting up the class. Original patch by Cheryl Sabella.

bpo-30899: IDLE: Add tests for ConfigParser subclasses in config. Patch by Louie Lu.

bpo-30881: IDLE: Add docstrings to browser.py. Patch by Cheryl Sabella.

bpo-30851: IDLE: Remove unused variables in configdialog. One is a duplicate, one is set but cannot be altered by users. Patch by Cheryl Sabella.

bpo-30870: IDLE: In Settings dialog, select font with Up, Down keys as well as mouse. Initial patch by Louie Lu.

bpo-8231: IDLE: call config.IdleConf.GetUserCfgDir only once.

bpo-30779: IDLE: Factor ConfigChanges class from configdialog, put in config; test. * In config, put dump test code in a function; run it and unittest in ‘if __name__ == ‘__main__’. * Add class config.ConfigChanges based on changes_class_v4.py on bpo issue. * Add class test_config.ChangesTest, partly using configdialog_tests_v1.py. * Revise configdialog to use ConfigChanges; see tracker msg297804. * Revise test_configdialog to match configdialog changes. * Remove configdialog functions unused or moved to ConfigChanges. Cheryl Sabella contributed parts of the patch.

bpo-30777: IDLE: configdialog - Add docstrings and fix comments. Patch by Cheryl Sabella.

bpo-30495: IDLE: Improve textview with docstrings, PEP8 names, and more tests. Patch by Cheryl Sabella.

bpo-30723: IDLE: Make several improvements to parenmatch. Add ‘parens’ style to highlight both opener and closer. Make ‘default’ style, which is not default, a synonym for ‘opener’. Make time-delay work the same with all styles. Add help for config dialog extensions tab, including help for parenmatch. Add new tests. Original patch by Charles Wohlganger.

bpo-30674: IDLE: add docstrings to grep module. Patch by Cheryl Sabella

bpo-21519: IDLE’s basic custom key entry dialog now detects duplicates properly. Original patch by Saimadhav Heblikar.

bpo-29910: IDLE no longer deletes a character after commenting out a region by a key shortcut. Add return 'break' for this and other potential conflicts between IDLE and default key bindings.

bpo-30728: Review and change idlelib.configdialog names. Lowercase method and attribute names. Replace ‘colour’ with ‘color’, expand overly cryptic names, delete unneeded underscores. Replace import * with specific imports. Patches by Cheryl Sabella.

bpo-6739: IDLE: Verify user-entered key sequences by trying to bind them with tk. Add tests for all 3 validation functions. Original patch by G Polo. Tests added by Cheryl Sabella.

bpo-30176: Add missing attribute related constants in curses documentation.

bpo-30052: the link targets for bytes() and bytearray() are now their respective type definitions, rather than the corresponding builtin function entries. Use bytes and bytearray to reference the latter.

In order to ensure this and future cross-reference updates are applied automatically, the daily documentation builds now disable the default output caching features in Sphinx.

bpo-26985: Add missing info of code object in inspect documentation.

bpo-27998: Fixed bytes path support in os.scandir() on Windows. Patch by Eryk Sun.

bpo-28317: The disassembler now decodes FORMAT_VALUE argument.

bpo-26293: Fixed writing ZIP files that starts not from the start of the file. Offsets in ZIP file now are relative to the start of the archive in conforming to the specification.

bpo-28380: unittest.mock Mock autospec functions now properly support assert_called, assert_not_called, and assert_called_once.

bpo-27181: remove statistics.geometric_mean and defer until 3.7.

bpo-28229: lzma module now supports pathlib.

bpo-28321: Fixed writing non-BMP characters with binary format in plistlib.

bpo-28225: bz2 module now supports pathlib. Initial patch by Ethan Furman.

bpo-28227: gzip now supports pathlib. Patch by Ethan Furman.

bpo-27358: Optimized merging var-keyword arguments and improved error message when passing a non-mapping as a var-keyword argument.

bpo-28257: Improved error message when passing a non-iterable as a var- positional argument. Added opcode BUILD_TUPLE_UNPACK_WITH_CALL.

bpo-28322: Fixed possible crashes when unpickle itertools objects from incorrect pickle data. Based on patch by John Leitch.

bpo-28228: imghdr now supports pathlib.

bpo-28226: compileall now supports pathlib.

bpo-28314: Fix function declaration (C flags) for the getiterator() method of xml.etree.ElementTree.Element.

bpo-28148: Stop using localtime() and gmtime() in the time module.

Introduced platform independent _PyTime_localtime API that is similar to POSIX localtime_r, but available on all platforms. Patch by Ed Schouten.

bpo-28253: Fixed calendar functions for extreme months: 0001-01 and 9999-12.

Methods itermonthdays() and itermonthdays2() are reimplemented so that they don’t call itermonthdates() which can cause datetime.date under/overflow.

bpo-28275: Fixed possible use after free in the decompress() methods of the LZMADecompressor and BZ2Decompressor classes. Original patch by John Leitch.

bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation() if pass invalid string-like object as a name. Patch by Xiang Zhang.

bpo-18844: random.choices() now has k as a keyword-only argument to improve the readability of common cases and come into line with the signature used in other languages.

bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py. Patch by Madison May.

bpo-27611: Fixed support of default root window in the tkinter.tix module. Added the master parameter in the DisplayStyle constructor.

bpo-27348: In the traceback module, restore the formatting of exception messages like “Exception: None”. This fixes a regression introduced in 3.5a2.

bpo-25651: Allow falsy values to be used for msg parameter of subTest().

bpo-27778: Fix a memory leak in os.getrandom() when the getrandom() is interrupted by a signal and a signal handler raises a Python exception.

bpo-28200: Fix memory leak on Windows in the os module (fix path_converter() function).

bpo-25400: RobotFileParser now correctly returns default values for crawl_delay and request_rate. Initial patch by Peter Wirtz.

bpo-27932: Prevent memory leak in win32_ver().

Fix UnboundLocalError in socket._sendfile_use_sendfile.

bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation of os.stat(). Patch by Eryk Sun.

bpo-22493: Warning message emitted by using inline flags in the middle of regular expression now contains a (truncated) regex pattern. Patch by Tim Graham.

bpo-25270: Prevent codecs.escape_encode() from raising SystemError when an empty bytestring is passed.

bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch by Gergely Imreh and Markus Holtermann.

bpo-28114: Fix a crash in parse_envlist() when env contains byte strings. Patch by Eryk Sun.

bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().

bpo-27906: Fix socket accept exhaustion during high TCP traffic. Patch by Kevin Conway.

bpo-28174: Handle when SO_REUSEPORT isn’t properly supported. Patch by Seth Michael Larson.

bpo-26654: Inspect functools.partial in asyncio.Handle.__repr__. Patch by iceboy.

bpo-26909: Fix slow pipes IO in asyncio. Patch by INADA Naoki.

bpo-28176: Fix callbacks race in asyncio.SelectorLoop.sock_connect.

bpo-27759: Fix selectors incorrectly retain invalid file descriptors. Patch by Mark Williams.

bpo-28368: Refuse monitoring processes if the child watcher has no loop attached. Patch by Vincent Michel.

bpo-28369: Raise RuntimeError when transport’s FD is used with add_reader, add_writer, etc.

bpo-28370: Speedup asyncio.StreamReader.readexactly. Patch by Коренберг Марк.

bpo-28371: Deprecate passing asyncio.Handles to run_in_executor.

bpo-28372: Fix asyncio to support formatting of non-python coroutines.

bpo-28399: Remove UNIX socket from FS before binding. Patch by Коренберг Марк.

bpo-27972: Prohibit Tasks to await on themselves.

bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked by SELinux and fails with EACCESS. The function now falls back to fcntl(). Patch written by Michał Bednarski.

bpo-27014: Fix infinite recursion using typing.py. Thanks to Kalle Tuure!

bpo-27031: Removed dummy methods in Tkinter widget classes: tk_menuBar() and tk_bindForTraversal().

bpo-14132: Fix urllib.request redirect handling when the target only has a query string. Original fix by Ján Janech.

bpo-17214: The “urllib.request” module now percent-encodes non-ASCII bytes found in redirect target URLs. Some servers send Location header fields with non- ASCII bytes, but “http.client” requires the request target to be ASCII- encodable, otherwise a UnicodeEncodeError is raised. Based on patch by Christian Heimes.

bpo-27033: The default value of the decode_data parameter for smtpd.SMTPChannel and smtpd.SMTPServer constructors is changed to False.

bpo-27034: Removed deprecated class asynchat.fifo.

bpo-26870: Added readline.set_auto_history(), which can stop entries being automatically added to the history list. Based on patch by Tyler Crompton.

bpo-26039: zipfile.ZipFile.open() can now be used to write data into a ZIP file, as well as for extracting data. Patch by Thomas Kluyver.

bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler. Patch contributed by Chi Hsuan Yen.

bpo-22274: In the subprocess module, allow stderr to be redirected to stdout even when stdout is not redirected. Patch by Akira Li.

bpo-26807: mock_open ‘files’ no longer error on readline at end of file. Patch from Yolanda Robla.

bpo-25745: Fixed leaking a userptr in curses panel destructor.

bpo-26977: Removed unnecessary, and ignored, call to sum of squares helper in statistics.pvariance.

bpo-26002: Use bisect in statistics.median instead of a linear search. Patch by Upendra Kuma.

bpo-25974: Make use of new Decimal.as_integer_ratio() method in statistics module. Patch by Stefan Krah.

bpo-26996: Add secrets module as described in PEP 506.

bpo-26881: The modulefinder module now supports extended opcode arguments.

bpo-23815: Fixed crashes related to directly created instances of types in _tkinter and curses.panel modules.

bpo-17765: weakref.ref() no longer silently ignores keyword arguments. Patch by Georg Brandl.

bpo-26873: xmlrpc now raises ResponseError on unsupported type tags instead of silently return incorrect result.

bpo-26915: The __contains__ methods in the collections ABCs now check for identity before checking equality. This better matches the behavior of the concrete classes, allows sensible handling of NaNs, and makes it easier to reason about container invariants.

bpo-26711: Fixed the comparison of plistlib.Data with other types.

bpo-24114: Fix an uninitialized variable in ctypes.util.

The bug only occurs on SunOS when the ctypes implementation searches for the crle program. Patch by Xiang Zhang. Tested on SunOS by Kees Bos.

bpo-26864: In urllib.request, change the proxy bypass host checking against no_proxy to be case-insensitive, and to not match unrelated host names that happen to have a bypassed hostname as a suffix. Patch by Xiang Zhang.

bpo-24902: Print server URL on http.server startup. Initial patch by Felix Kaiser.

bpo-25788: fileinput.hook_encoded() now supports an “errors” argument for passing to open. Original patch by Joseph Hackman.

bpo-26634: recursive_repr() now sets __qualname__ of wrapper. Patch by Xiang Zhang.

bpo-26804: urllib.request will prefer lower_case proxy environment variables over UPPER_CASE or Mixed_Case ones. Patch contributed by Hans- Peter Jansen.

bpo-26837: assertSequenceEqual() now correctly outputs non-stringified differing items (like bytes in the -b mode). This affects assertListEqual() and assertTupleEqual().

bpo-26041: Remove “will be removed in Python 3.7” from deprecation messages of platform.dist() and platform.linux_distribution(). Patch by Kumaripaba Miyurusara Athukorala.

bpo-26822: itemgetter, attrgetter and methodcaller objects no longer silently ignore keyword arguments.

bpo-26733: Disassembling a class now disassembles class and static methods. Patch by Xiang Zhang.

bpo-26801: Fix error handling in shutil.get_terminal_size(), catch AttributeError instead of NameError. Patch written by Emanuel Barry.

bpo-24838: tarfile’s ustar and gnu formats now correctly calculate name and link field limits for multibyte character encodings like utf-8.

bpo-15812: inspect.getframeinfo() now correctly shows the first line of a context. Patch by Sam Breese.

bpo-29094: Offsets in a ZIP file created with extern file object and modes “w” and “x” now are relative to the start of the file.

bpo-13051: Fixed recursion errors in large or resized curses.textpad.Textbox. Based on patch by Tycho Andersen.

bpo-29119: Fix weakrefs in the pure python version of collections.OrderedDict move_to_end() method. Contributed by Andra Bogildea.

bpo-9770: curses.ascii predicates now work correctly with negative integers.

bpo-28427: old keys should not remove new values from WeakValueDictionary when collecting from another thread.

bpo-28923: Remove editor artifacts from Tix.py.

bpo-28871: Fixed a crash when deallocate deep ElementTree.

bpo-19542: Fix bugs in WeakValueDictionary.setdefault() and WeakValueDictionary.pop() when a GC collection happens in another thread.

bpo-20191: Fixed a crash in resource.prlimit() when pass a sequence that doesn’t own its elements as limits.

bpo-28779: multiprocessing.set_forkserver_preload() would crash the forkserver process if a preloaded module instantiated some multiprocessing objects such as locks.

bpo-28847: dbm.dumb now supports reading read-only files and no longer writes the index file when it is not changed.

bpo-25659: In ctypes, prevent a crash calling the from_buffer() and from_buffer_copy() methods on abstract classes like Array.

bpo-28732: Fix crash in os.spawnv() with no elements in args

bpo-28485: Always raise ValueError for negative compileall.compile_dir(workers=…) parameter, even when multithreading is unavailable.

bpo-28387: Fixed possible crash in _io.TextIOWrapper deallocator when the garbage collector is invoked in other thread. Based on patch by Sebastian Cufre.

bpo-27517: LZMA compressor and decompressor no longer raise exceptions if given empty data twice. Patch by Benjamin Fogle.

bpo-28549: Fixed segfault in curses’s addch() with ncurses6.

bpo-28449: tarfile.open() with mode “r” or “r:” now tries to open a tar file with compression before trying to open it without compression. Otherwise it had 50% chance failed with ignore_zeros=True.

bpo-23262: The webbrowser module now supports Firefox 36+ and derived browsers. Based on patch by Oleg Broytman.

bpo-27939: Fixed bugs in tkinter.ttk.LabeledScale and tkinter.Scale caused by representing the scale as float value internally in Tk. tkinter.IntVar now works if float value is set to underlying Tk variable.

bpo-28255: calendar.TextCalendar().prmonth() no longer prints a space at the start of new line after printing a month’s calendar. Patch by Xiang Zhang.

bpo-20491: The textwrap.TextWrapper class now honors non-breaking spaces. Based on patch by Kaarle Ritvanen.

bpo-28353: os.fwalk() no longer fails on broken links.

bpo-25464: Fixed HList.header_exists() in tkinter.tix module by addin a workaround to Tix library bug.

bpo-28488: shutil.make_archive() no longer add entry “./” to ZIP archive.

bpo-24452: Make webbrowser support Chrome on Mac OS X.

bpo-20766: Fix references leaked by pdb in the handling of SIGINT handlers.

bpo-26293: Fixed writing ZIP files that starts not from the start of the file. Offsets in ZIP file now are relative to the start of the archive in conforming to the specification.

bpo-28321: Fixed writing non-BMP characters with binary format in plistlib.

bpo-28322: Fixed possible crashes when unpickle itertools objects from incorrect pickle data. Based on patch by John Leitch.

Fix possible integer overflows and crashes in the mmap module with unusual usage patterns.

bpo-1703178: Fix the ability to pass the –link-objects option to the distutils build_ext command.

bpo-28253: Fixed calendar functions for extreme months: 0001-01 and 9999-12.

Methods itermonthdays() and itermonthdays2() are reimplemented so that they don’t call itermonthdates() which can cause datetime.date under/overflow.

bpo-28275: Fixed possible use after free in the decompress() methods of the LZMADecompressor and BZ2Decompressor classes. Original patch by John Leitch.

bpo-27897: Fixed possible crash in sqlite3.Connection.create_collation() if pass invalid string-like object as a name. Patch by Xiang Zhang.

bpo-18893: Fix invalid exception handling in Lib/ctypes/macholib/dyld.py. Patch by Madison May.

bpo-27611: Fixed support of default root window in the tkinter.tix module.

bpo-27348: In the traceback module, restore the formatting of exception messages like “Exception: None”. This fixes a regression introduced in 3.5a2.

bpo-25651: Allow falsy values to be used for msg parameter of subTest().

bpo-27932: Prevent memory leak in win32_ver().

Fix UnboundLocalError in socket._sendfile_use_sendfile.

bpo-28075: Check for ERROR_ACCESS_DENIED in Windows implementation of os.stat(). Patch by Eryk Sun.

bpo-25270: Prevent codecs.escape_encode() from raising SystemError when an empty bytestring is passed.

bpo-28181: Get antigravity over HTTPS. Patch by Kaartic Sivaraam.

bpo-25895: Enable WebSocket URL schemes in urllib.parse.urljoin. Patch by Gergely Imreh and Markus Holtermann.

bpo-27599: Fixed buffer overrun in binascii.b2a_qp() and binascii.a2b_qp().

bpo-19003: m email.generator now replaces only \r and/or \n line endings, per the RFC, instead of all unicode line endings.

bpo-28019: itertools.count() no longer rounds non-integer step in range between 1.0 and 2.0 to 1.

bpo-25969: Update the lib2to3 grammar to handle the unpacking generalizations added in 3.5.

bpo-14977: mailcap now respects the order of the lines in the mailcap files (“first match”), as required by RFC 1542. Patch by Michael Lazar.

bpo-24594: Validates persist parameter when opening MSI database

bpo-17582: xml.etree.ElementTree nows preserves whitespaces in attributes (Patch by Duane Griffin. Reviewed and approved by Stefan Behnel.)

bpo-28047: Fixed calculation of line length used for the base64 CTE in the new email policies.

bpo-27445: Don’t pass str(_charset) to MIMEText.set_payload(). Patch by Claude Paroz.

bpo-22450: urllib now includes an Accept: */* header among the default headers. This makes the results of REST API requests more consistent and predictable especially when proxy servers are involved.

lib2to3.pgen3.driver.load_grammar() now creates a stable cache file between runs given the same Grammar.txt input regardless of the hash randomization setting.

bpo-27570: Avoid zero-length memcpy() etc calls with null source pointers in the “ctypes” and “array” modules.

bpo-22233: Break email header lines only on the RFC specified CR and LF characters, not on arbitrary unicode line breaks. This also fixes a bug in HTTP header parsing.

bpo-27988: Fix email iter_attachments incorrect mutation of payload list.

bpo-27691: Fix ssl module’s parsing of GEN_RID subject alternative name fields in X.509 certs.

bpo-27850: Remove 3DES from ssl module’s default cipher list to counter measure sweet32 attack (CVE-2016-2183).

bpo-27766: Add ChaCha20 Poly1305 to ssl module’s default ciper list. (Required OpenSSL 1.1.0 or LibreSSL).

bpo-26470: Port ssl and hashlib module to OpenSSL 1.1.0.

Remove support for passing a file descriptor to os.access. It never worked but previously didn’t raise.

bpo-12885: Fix error when distutils encounters symlink.

bpo-27881: Fixed possible bugs when setting sqlite3.Connection.isolation_level. Based on patch by Xiang Zhang.

bpo-27861: Fixed a crash in sqlite3.Connection.cursor() when a factory creates not a cursor. Patch by Xiang Zhang.

bpo-19884: Avoid spurious output on OS X with Gnu Readline.

bpo-27706: Restore deterministic behavior of random.Random().seed() for string seeds using seeding version 1. Allows sequences of calls to random() to exactly match those obtained in Python 2. Patch by Nofar Schnider.

bpo-10513: Fix a regression in Connection.commit(). Statements should not be reset after a commit.

A new version of typing.py from https://github.com/python/typing: - Collection (only for 3.6) (bpo-27598) - Add FrozenSet to __all__ (upstream #261) - fix crash in _get_type_vars() (upstream #259) - Remove the dict constraint in ForwardRef._eval_type (upstream #252)

bpo-27539: Fix unnormalised Fraction.__pow__ result in the case of negative exponent and negative base.

bpo-21718: cursor.description is now available for queries using CTEs.

bpo-2466: posixpath.ismount now correctly recognizes mount points which the user does not have permission to access.

bpo-27773: Correct some memory management errors server_hostname in _ssl.wrap_socket().

bpo-26750: unittest.mock.create_autospec() now works properly for subclasses of property() and other data descriptors.

In the curses module, raise an error if window.getstr() or window.instr() is passed a negative value.

bpo-27783: Fix possible usage of uninitialized memory in operator.methodcaller.

bpo-27774: Fix possible Py_DECREF on unowned object in _sre.

bpo-27760: Fix possible integer overflow in binascii.b2a_qp.

bpo-27758: Fix possible integer overflow in the _csv module for large record lengths.

bpo-27568: Prevent HTTPoxy attack (CVE-2016-1000110). Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which indicates that the script is in CGI mode.

bpo-27656: Do not assume sched.h defines any SCHED_* constants.

bpo-27130: In the “zlib” module, fix handling of large buffers (typically 4 GiB) when compressing and decompressing. Previously, inputs were limited to 4 GiB, and compression and decompression operations did not properly handle results of 4 GiB.

bpo-27533: Release GIL in nt._isdir

bpo-17711: Fixed unpickling by the persistent ID with protocol 0. Original patch by Alexandre Vassalotti.

bpo-27522: Avoid an unintentional reference cycle in email.feedparser.

bpo-26844: Fix error message for imp.find_module() to refer to ‘path’ instead of ‘name’. Patch by Lev Maximov.

bpo-23804: Fix SSL zero-length recv() calls to not block and not raise an error about unclean EOF.

bpo-27466: Change time format returned by http.cookie.time2netscape, confirming the netscape cookie format and making it consistent with documentation.

bpo-26664: Fix activate.fish by removing mis-use of $.

bpo-22115: Fixed tracing Tkinter variables: trace_vdelete() with wrong mode no longer break tracing, trace_vinfo() now always returns a list of pairs of strings, tracing in the “u” mode now works.

Fix a scoping issue in importlib.util.LazyLoader which triggered an UnboundLocalError when lazy-loading a module that was already put into sys.modules.

bpo-27079: Fixed curses.ascii functions isblank(), iscntrl() and ispunct().

bpo-26754: Some functions (compile() etc) accepted a filename argument encoded as an iterable of integers. Now only strings and byte-like objects are accepted.

bpo-27048: Prevents distutils failing on Windows when environment variables contain non-ASCII characters

bpo-27330: Fixed possible leaks in the ctypes module.

bpo-27238: Got rid of bare excepts in the turtle module. Original patch by Jelle Zijlstra.

bpo-27122: When an exception is raised within the context being managed by a contextlib.ExitStack() and one of the exit stack generators catches and raises it in a chain, do not re-raise the original exception when exiting, let the new chained one through. This avoids the PEP 479 bug described in issue25782.

bpo-27164: In the zlib module, allow decompressing raw Deflate streams with a predefined zdict. Based on patch by Xiang Zhang.

bpo-24291: Fix wsgiref.simple_server.WSGIRequestHandler to completely write data to the client. Previously it could do partial writes and truncate data. Also, wsgiref.handler.ServerHandler can now handle stdout doing partial writes, but this is deprecated.

bpo-26809: Add __all__ to string. Patch by Emanuel Barry.

bpo-26373: subprocess.Popen.communicate now correctly ignores BrokenPipeError when the child process dies before .communicate() is called in more/all circumstances.

bpo-21776: distutils.upload now correctly handles HTTPError. Initial patch by Claudiu Popa.

bpo-27114: Fix SSLContext._load_windows_store_certs fails with PermissionError

bpo-18383: Avoid creating duplicate filters when using filterwarnings and simplefilter. Based on patch by Alex Shkop.

bpo-27057: Fix os.set_inheritable() on Android, ioctl() is blocked by SELinux and fails with EACCESS. The function now falls back to fcntl(). Patch written by Michał Bednarski.

bpo-27014: Fix infinite recursion using typing.py. Thanks to Kalle Tuure!

bpo-14132: Fix urllib.request redirect handling when the target only has a query string. Original fix by Ján Janech.

bpo-17214: The “urllib.request” module now percent-encodes non-ASCII bytes found in redirect target URLs. Some servers send Location header fields with non- ASCII bytes, but “http.client” requires the request target to be ASCII- encodable, otherwise a UnicodeEncodeError is raised. Based on patch by Christian Heimes.

bpo-26892: Honor debuglevel flag in urllib.request.HTTPHandler. Patch contributed by Chi Hsuan Yen.

bpo-22274: In the subprocess module, allow stderr to be redirected to stdout even when stdout is not redirected. Patch by Akira Li.

bpo-26807: mock_open ‘files’ no longer error on readline at end of file. Patch from Yolanda Robla.

bpo-25745: Fixed leaking a userptr in curses panel destructor.

bpo-26977: Removed unnecessary, and ignored, call to sum of squares helper in statistics.pvariance.

bpo-26881: The modulefinder module now supports extended opcode arguments.

bpo-23815: Fixed crashes related to directly created instances of types in _tkinter and curses.panel modules.

bpo-17765: weakref.ref() no longer silently ignores keyword arguments. Patch by Georg Brandl.

bpo-26873: xmlrpc now raises ResponseError on unsupported type tags instead of silently return incorrect result.

bpo-26711: Fixed the comparison of plistlib.Data with other types.

bpo-24114: Fix an uninitialized variable in ctypes.util.

The bug only occurs on SunOS when the ctypes implementation searches for the crle program. Patch by Xiang Zhang. Tested on SunOS by Kees Bos.

bpo-26864: In urllib.request, change the proxy bypass host checking against no_proxy to be case-insensitive, and to not match unrelated host names that happen to have a bypassed hostname as a suffix. Patch by Xiang Zhang.

bpo-26634: recursive_repr() now sets __qualname__ of wrapper. Patch by Xiang Zhang.

bpo-26804: urllib.request will prefer lower_case proxy environment variables over UPPER_CASE or Mixed_Case ones. Patch contributed by Hans- Peter Jansen.

bpo-26837: assertSequenceEqual() now correctly outputs non-stringified differing items (like bytes in the -b mode). This affects assertListEqual() and assertTupleEqual().

bpo-26041: Remove “will be removed in Python 3.7” from deprecation messages of platform.dist() and platform.linux_distribution(). Patch by Kumaripaba Miyurusara Athukorala.

bpo-26822: itemgetter, attrgetter and methodcaller objects no longer silently ignore keyword arguments.

bpo-26733: Disassembling a class now disassembles class and static methods. Patch by Xiang Zhang.

bpo-26801: Fix error handling in shutil.get_terminal_size(), catch AttributeError instead of NameError. Patch written by Emanuel Barry.

bpo-24838: tarfile’s ustar and gnu formats now correctly calculate name and link field limits for multibyte character encodings like utf-8.

bpo-22524: New os.scandir() function, part of the PEP 471: “os.scandir() function – a better and faster directory iterator”. Patch written by Ben Hoyt.

bpo-23103: Reduced the memory consumption of IPv4Address and IPv6Address.

bpo-21793: BaseHTTPRequestHandler again logs response code as numeric, not as stringified enum. Patch by Demian Brecht.

bpo-23476: In the ssl module, enable OpenSSL’s X509_V_FLAG_TRUSTED_FIRST flag on certificate stores when it is available.

bpo-23576: Avoid stalling in SSL reads when EOF has been reached in the SSL layer but the underlying connection hasn’t been closed.

bpo-23504: Added an __all__ to the types module.

bpo-23563: Optimized utility functions in urllib.parse.

bpo-7830: Flatten nested functools.partial.

bpo-20204: Added the __module__ attribute to _tkinter classes.

bpo-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.

bpo-23521: Corrected pure python implementation of timedelta division.

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

bpo-21619: Popen objects no longer leave a zombie after exit in the with statement if the pipe was broken. Patch by Martin Panter.

bpo-22936: Make it possible to show local variables in tracebacks for both the traceback module and unittest.

bpo-15955: Add an option to limit the output size in bz2.decompress(). Patch by Nikolaus Rath.

bpo-6639: Module-level turtle functions no longer raise TclError after closing the window.

bpo-814253: Group references and conditional group references now work in lookbehind assertions in regular expressions. (See also: bpo-9179)

bpo-23215: Multibyte codecs with custom error handlers that ignores errors consumed too much memory and raised SystemError or MemoryError. Original patch by Aleksi Torhamo.

bpo-5700: io.FileIO() called flush() after closing the file. flush() was not called in close() if closefd=False.

bpo-23374: Fixed pydoc failure with non-ASCII files when stdout encoding differs from file system encoding (e.g. on Mac OS).

bpo-23481: Remove RC4 from the SSL module’s default cipher list.

bpo-21548: Fix pydoc.synopsis() and pydoc.apropos() on modules with empty docstrings.

bpo-22885: Fixed arbitrary code execution vulnerability in the dbm.dumb module. Original patch by Claudiu Popa.

bpo-23239: ssl.match_hostname() now supports matching of IP addresses.

bpo-23146: Fix mishandling of absolute Windows paths with forward slashes in pathlib.

bpo-23096: Pickle representation of floats with protocol 0 now is the same for both Python and C implementations.

bpo-19105: pprint now more efficiently uses free space at the right.

bpo-14910: Add allow_abbrev parameter to argparse.ArgumentParser. Patch by Jonathan Paugh, Steven Bethard, paul j3 and Daniel Eriksson.

bpo-21717: tarfile.open() now supports ‘x’ (exclusive creation) mode.

bpo-23344: marshal.dumps() is now 20-25% faster on average.

bpo-20416: marshal.dumps() with protocols 3 and 4 is now 40-50% faster on average.

bpo-23421: Fixed compression in tarfile CLI. Patch by wdv4758h.

bpo-23367: Fix possible overflows in the unicodedata module.

bpo-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.

bpo-19705: turtledemo now has a visual sorting algorithm demo. Original patch from Jason Yeo.

bpo-23801: Fix issue where cgi.FieldStorage did not always ignore the entire preamble to a multipart body.