Python 3.7.7 final
Library
bpo-13487: Avoid a possible “RuntimeError: dictionary changed size during iteration” from inspect.getmodule() when it tried to loop through sys.modules.
Documentation
bpo-17422: The language reference no longer restricts default class namespaces to dicts only.
Python 3.7.7 release candidate 1
Security
bpo-39401: Avoid unsafe load of api-ms-win-core-path-l1-1-0.dll at startup on Windows 7.
Core and Builtins
bpo-39776: Fix race condition where threads created by PyGILState_Ensure() could get a duplicate id.
This affects consumers of tstate->id like the contextvar caching machinery, which could return invalid cached objects under heavy thread load (observed in embedded scenarios).
bpo-39778: Fixed a crash due to incorrect handling of weak references in collections.OrderedDict classes. Patch by Pablo Galindo.
bpo-39382: Fix a use-after-free in the single inheritance path of issubclass(), when the __bases__ of an object has a single reference, and so does its first item. Patch by Yonatan Goldschmidt.
bpo-39606: Fix regression caused by fix for bpo-39386, that prevented calling aclose on an async generator that had already been closed or exhausted.
bpo-39510: Fix segfault in readinto() method on closed BufferedReader.
bpo-39453: Fixed a possible crash in list.__contains__() when a list is changed during comparing items. Patch by Dong-hee Na.
bpo-39427: Document all possibilities for the -X options in the command line help section. Patch by Pablo Galindo.
bpo-39421: Fix possible crashes when operating with the functions in the heapq module and custom comparison operators.
bpo-39386: Prevent double awaiting of async iterator.
bpo-38588: Fix possible crashes in dict and list when calling PyObject_RichCompareBool().
bpo-39031: When parsing an “elif” node, lineno and col_offset of the node now point to the “elif” keyword and not to its condition, making it consistent with the “if” node. Patch by Lysandros Nikolaou.
bpo-38610: Fix possible crashes in several list methods by holding strong references to list elements when calling PyObject_RichCompareBool().
Library
bpo-39794: Add –without-decimal-contextvar build option. This enables a thread-local rather than a coroutine local context.
bpo-39769: The compileall.compile_dir() function’s ddir parameter and the compileall command line flag -d no longer write the wrong pathname to the generated pyc file for submodules beneath the root of the directory tree being compiled. This fixes a regression introduced with Python 3.5.
bpo-30566: Fix IndexError when trying to decode an invalid string with punycode codec.
bpo-39649: Remove obsolete check for __args__ in bdb.Bdb.format_stack_entry.
bpo-27657: The original fix for bpo-27657, “Fix urlparse() with numeric paths” (GH-16839) included in 3.7.6, inadvertently introduced a behavior change that broke several third-party packages relying on the original undefined parsing behavior. The change is reverted in 3.7.7, restoring the behavior of 3.7.5 and earlier releases.
bpo-21016: The pydoc and trace modules now use the sysconfig module to get the path to the Python standard library, to support uncommon installation path like /usr/lib64/python3.9/ on Fedora. Patch by Jan Matějek.
bpo-39548: Fix handling of header in urllib.request.AbstractDigestAuthHandler when the optional qop parameter is not present.
bpo-39450: Striped whitespace from docstring before returning it from unittest.case.shortDescription().
bpo-39493: Mark typing.IO.closed as a property
bpo-39485: Fix a bug in unittest.mock.create_autospec() that would complain about the wrong number of arguments for custom descriptors defined in an extension module returning functions.
bpo-39430: Fixed race condition in lazy imports in tarfile.
bpo-39389: Write accurate compression level metadata in gzip archives, rather than always signaling maximum compression.
bpo-39274: bool(fraction.Fraction) now returns a boolean even if (numerator != 0) does not return a boolean (ex: numpy number).
bpo-39242: Updated the Gmane domain from news.gmane.org to news.gmane.io which is used for examples of NNTP news reader server and nntplib tests.
bpo-39152: Fix ttk.Scale.configure([name]) to return configuration tuple for name or all options. Giovanni Lombardo contributed part of the patch.
bpo-39198: If an exception were to be thrown in Logger.isEnabledFor (say, by asyncio timeouts or stopit) , the logging global lock may not be released appropriately, resulting in deadlock. This change wraps that block of code with try...finally to ensure the lock is released.
bpo-39191: Perform a check for running loop before starting a new task in loop.run_until_complete() to fail fast; it prevents the side effect of new task spawning before exception raising.
bpo-38871: Correctly parenthesize filter-based statements that contain lambda expressions in mod:lib2to3. Patch by Dong-hee Na.
bpo-39142: A change was made to logging.config.dictConfig to avoid converting instances of named tuples to ConvertingTuple. It’s assumed that named tuples are too specialised to be treated like ordinary tuples; if a user of named tuples requires ConvertingTuple functionality, they will have to implement that themselves in their named tuple class.
bpo-38971: Open issue in the BPO indicated a desire to make the implementation of codecs.open() at parity with io.open(), which implements a try/except to assure file stream gets closed before an exception is raised.
bpo-39057: urllib.request.proxy_bypass_environment() now ignores leading dots and no longer ignores a trailing newline.
bpo-39056: Fixed handling invalid warning category in the -W option. No longer import the re module if it is not needed.
bpo-39055: base64.b64decode() with validate=True raises now a binascii.Error if the input ends with a single \n.
bpo-38878: Fixed __subclasshook__ of os.PathLike to return a correct result upon inheritence. Patch by Bar Harel.
bpo-35182: Fixed Popen.communicate() subsequent call crash when the child process has already closed any piped standard stream, but still continues to be running. Patch by Andriy Maletsky.
bpo-38473: Use signature from inner mock for autospecced methods attached with unittest.mock.attach_mock(). Patch by Karthikeyan Singaravelan.
bpo-38293: Add copy.copy() and copy.deepcopy() support to property() objects.
bpo-37953: In typing, improved the __hash__ and __eq__ methods for ForwardReferences.
bpo-36406: Handle namespace packages in doctest. Patch by Karthikeyan Singaravelan.
Documentation
bpo-13790: Change ‘string’ to ‘specification’ in format doc.
bpo-39530: Fix misleading documentation about mixed-type numeric comparisons.
bpo-17422: The language reference now specifies restrictions on class namespaces. Adapted from a patch by Ethan Furman.
bpo-39654: In pyclbr doc, update ‘class’ to ‘module’ where appropriate and add readmodule comment. Patch by Hakan Çelik.
bpo-39392: Explain that when filling with turtle, overlap regions may be left unfilled.
bpo-39381: Mention in docs that asyncio.get_event_loop() implicitly creates new event loop only if called from the main thread.
bpo-38918: Add an entry for __module__ in the “function” & “method” sections of the inspect docs types and members table
bpo-3530: In the ast module documentation, fix a misleading NodeTransformer example and add advice on when to use the fix_missing_locations function.
Tests
bpo-38546: Fix test_ressources_gced_in_workers() of test_concurrent_futures: explicitly stop the manager to prevent leaking a child process running in the background after the test completes.
Build
bpo-39144: The ctags and etags build targets both include Modules/_ctypes and Python standard library source files.
Windows
bpo-38597: distutils will no longer statically link vcruntime140.dll when a redistributable version is unavailable. All future releases of CPython will include a copy of this DLL to ensure distributed extensions can continue to load.
bpo-38380: Update Windows builds to use SQLite 3.31.1
bpo-39439: Reduce overhead when using multiprocessing in a Windows virtual environment
bpo-39185: The build.bat script has additional options for very-quiet output (-q) and very-verbose output (-vv)
macOS
bpo-38380: Update macOS builds to use SQLite 3.31.1
IDLE
bpo-39781: Selecting code context lines no longer causes a jump.
bpo-39663: Add tests for pyparse find_good_parse_start().
bpo-39600: In the font configuration window, remove duplicated font names.
bpo-30780: Add remaining configdialog tests for buttons and highlights and keys tabs.
bpo-39388: IDLE Settings Cancel button now cancels pending changes
bpo-39050: Make IDLE Settings dialog Help button work again.
bpo-34118: Tag memoryview, range, and tuple as classes, the same as list, etcetera, in the library manual built-in functions list.
bpo-38792: Close an IDLE shell calltip if a KeyboardInterrupt or shell restart occurs. Patch by Zackery Spytz.
bpo-32989: Add tests for editor newline_and_indent_event method. Remove dead code from pyparse find_good_parse_start method.
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