bpo-35621: Support running subprocesses in asyncio when loop is executed in non-main thread  (GH-14344)

Add more fuzz testing for re.compile, re.load and csv.reader

* Added documentation for textwrap.dedent behavior.
* Remove an obsolete note about pre-2.5 behavior from the docstring.

sys._base_executable is now always defined on all platforms, and can be overridden through configuration.
Also adds test.support.PythonSymlink to encapsulate platform-specific logic for symlinking sys.executable

Also renamed the file to "test_pkg_import.py" to better follow the naming convention. Component of issue 19696.





https://bugs.python.org/issue19696

Add a versionadded for PS Core and note that `.venv` is a common virtual environment name.

* bpo-31783: Fix a race condition while creating workers during interpreter shutdown

* 📜🤖 Added by blurb_it.

As noted by @eryksun in [1] and [2], using _cleanup and _active(in
__del__) is not necessary on Windows, since:

> Unlike Unix, a process in Windows doesn't have to be waited on by
> its parent to avoid a zombie. Keeping the handle open will actually
> create a zombie until the next _cleanup() call, which may be never
> if Popen() isn't called again.

This patch simply defines `subprocess._active` as `None`, for which we already
have the proper logic in place in `subprocess.Popen.__del__`, that prevents it
from trying to append the process to the `_active`. This patch also defines
`subprocess._cleanup` as a noop for Windows.

[1] https://bugs.python.org/issue37380#msg346333
[2] https://bugs.python.org/issue36067#msg336262Signed-off-by: Ruslan Kuprieiev <ruslan@iterative.ai>

On Windows, test.pythoninfo now checks if support for long paths is
enabled using ntdll.RtlAreLongPathsEnabled() function.
Co-Authored-By: Eryk Sun <eryksun@gmail.com>

* Fix test for integer overflow.
* Add an unit test.

Don't call _Py_isabs() with a bytes string (char*), the function
expects as wide string.

Also updates some (unreleased) event names to be consistent with the others.

When libc_ver() is called with an executable, the
os.confstr('CS_GNU_LIBC_VERSION') fast-path cannot be taken. Modify
platform.platform() to call libc_ver() without executable, instead of
calling libc_ver(sys.executable), since sys.executable is already the
default value.

* Fix typo in supports_file2file_sendfile(); ensure that dst is
  removed
* Fix test_copytree_custom_copy_function(): remove dst tree.
  Use support.rmtree() rather than shutil.rmtree() to remove
  temporary directories: support tries harder.

https://bugs.python.org/issue37376

Use Py_ssize_t instead of int for i.

* patched string index out of range error in get_word function of _header_value_parser.py and created tests in test__header_value_parser.py for CFWS.
* Raise HeaderParseError instead of continuing when parsing a word.

Fix test_wsgiref.testEnviron() to no longer depend on the environment
variables (don't fail if "X" variable is set).

testEnviron() now overrides os.environ to get a deterministic
environment. Test full TestHandler.environ content: not only a few
selected variables.

Remove the undocumented sys.callstats() function. Since Python 3.7,
it was deprecated and always returned None. It required a special
build option CALL_PROFILE which was already removed in Python 3.7.

The os.getcwdb() function now uses the UTF-8 encoding on Windows,
rather than the ANSI code page: see PEP 529 for the rationale. The
function is no longer deprecated on Windows.

os.getcwd() and os.getcwdb() now detect integer overflow on memory
allocations. On Unix, these functions properly report MemoryError on
memory allocation failure.

The sqlite3 module now raises TypeError, rather than ValueError, if
operation argument type is not str: execute(), executemany() and
calling a connection.

Add a fast-path to PyUnicode_Decode() for size equals to 0.

In development mode and in debug build, encoding and errors arguments
are now checked on string encoding and decoding operations. Examples:
open(), str.encode() and bytes.decode().

By default, for best performances, the errors argument is only
checked at the first encoding/decoding error, and the encoding
argument is sometimes ignored for empty strings.

Increase robustness of test_resource_tracker(): retry for 60 seconds.