See also PR GH-13148.

The ``__rmod__`` method of ``collections.UserString`` class had a bug that made it unusable. 


https://bugs.python.org/issue25652

Co-Authored-By: Yury Selivanov <yury@magic.io>

Add an extend action to argparse


https://bugs.python.org/issue23378

Links creating an infinite symlink loop would raise an exception.

* bpo-36929: Modify io/re tests to allow for missing mod name

For a vanishingly small number of internal types, CPython sets the
tp_name slot to mod_name.type_name, either in the PyTypeObject or the
PyType_Spec. There are a few minor places where this surfaces:

* Custom repr functions for those types (some of which ignore the
  tp_name in favor of using a string literal, such as _io.TextIOWrapper)
* Pickling error messages

The test suite only tests the former. This commit modifies the test
suite to allow Python implementations to omit the module prefix.

https://bugs.python.org/issue36929

The mmap module set MAP_SHARED flag when map anonymous memory, however VxWorks
only support MAP_PRIVATE when map anonymous memory, this commit clear MAP_SHARED
and set MAP_PRIVATE.

This reverts commit 4959c33d.

Include windows.h rather than crtdbg.h to get STATUS_CONTROL_C_EXIT constant.
Moreover, include windows.h on Windows, not only when MSC is used.

* This PR fixes the `RuntimeWarning` in `inspect.isawaitable(mock())` where `mock()` was not awaited.
* Fix typo in asynctest project.

.. And update some deprecation warnings with version numbers.




https://bugs.python.org/issue36932

This parameter is marked as deprecated since 3.6 and for removal in 3.8.
It already had no effects.

https://bugs.python.org/issue23896

_PyRuntime.preconfig.coerce_c_locale can now be used to
check if the C locale has been coerced.

* Fix _Py_LegacyLocaleDetected(): don't attempt to coerce the
  C locale if LC_ALL environment variable is set. Add 'warn'
  parameter: emit_stderr_warning_for_legacy_locale() must not
  the LC_ALL env var.
* _PyPreConfig_Write() sets coerce_c_locale to 0 if
  _Py_CoerceLegacyLocale() fails.

* Fix encoding and locale tests in test_embed.InitConfigTests.
* InitConfigTests now only computes EXPECTED_CONFIG once.
* Add tests for PYTHONWARNINGS and PYTHONPATH env vars

This slightly expands an existing test case `test_popen_error` to trigger a `ResourceWarning` and fixes it.


https://bugs.python.org/issue35721

* Add _PyPreConfig.parse_argv
* Add _PyCoreConfig._config_init field and _PyCoreConfigInitEnum enum
  type
* Initialization functions: reject preconfig=NULL and config=NULL
* Add config parameter to _PyCoreConfig_DecodeLocaleErr(): pass
  config->argv to _Py_PreInitializeFromPyArgv(), to parse config
  command line arguments in preinitialization.
* Add config parameter to _PyCoreConfig_SetString(). It now
  preinitializes Python.
* _PyCoreConfig_SetPyArgv() now also preinitializes Python for wide
  argv
* Fix _Py_PreInitializeFromCoreConfig(): don't pass args to
  _Py_PreInitializeFromPyArgv() if config.parse_argv=0.
* Use "char * const *" and "wchar_t * const *" types for 'argv'
  parameters and _PyArgv.argv.
* Add unit test on preinitialization from argv.
* _PyPreConfig.allocator type becomes int
* Add _PyPreConfig_InitFromPreConfig() and
  _PyPreConfig_InitFromCoreConfig() helper functions

Print any argument other than None or int passed to SystemExit
or sys.exit().

Add new cpython/traceback.h and pycore_traceback.h header files to
Makefile.pre.in and PCbuild/ project.

Add new Include/cpython/traceback.h and Include/internal/traceback.h
header files.

The sqlit3.Connection object doesn't call its close() method when it's used
as a context manager.

* Add math.isqrt function computing the integer square root.

* Code cleanup: remove redundant comments, rename some variables.

* Tighten up code a bit more; use Py_XDECREF to simplify error handling.

* Update Modules/mathmodule.c
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>

* Update Modules/mathmodule.c

Use real argument clinic type instead of an alias
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>

* Add proof sketch

* Updates from review.

* Correct and expand documentation.

* Fix bad reference handling on error; make some variables block-local; other tidying.

* Style and consistency fixes.

* Add missing error check; don't try to DECREF a NULL a

* Simplify some error returns.

* Another two test cases:

- clarify that floats are rejected even if they happen to be
  squares of small integers
- TypeError beats ValueError for a negative float

* Add fast path for small inputs. Needs tests.

* Speed up isqrt for n >= 2**64 as well; add extra tests.

* Reduce number of test-cases to avoid dominating the run-time of test_math.

* Don't perform unnecessary extra iterations when computing c_bit_length.

* Abstract common uint64_t code out into a separate function.

* Cleanup.

* Add a missing Py_DECREF in an error branch. More cleanup.

* Update Modules/mathmodule.c

Add missing `static` declaration to helper function.
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>

* Add missing backtick.

Add a missing comma.