bpo-28238: Implement "{*}tag" and "{ns}*" wildcard tag selection support for ElementPath, and extend the surrounding tests and docs. (GH-12997)

Given example does not run, loop variable is missing.

Secondly, this is bad example how to handle shutdown signal, because it would cause `RuntimeError: Event loop stopped before Future completed.`

Perhaps it would be better to cancel all tasks instead of closing loop directly?

Did not create issue, because question is quite simple.

Call remove_done_callback() in finally block.


https://bugs.python.org/issue36613

Those tests may fail with PermissionError.



https://bugs.python.org/issue36341

Prefer the full wording instead, as it is more meaningful for someone not familiar with the terms.

Also, LFS/RHS is not used anywhere else in the documentation, while left/right-hand side mentions are common.

_PyCoreConfig_SetPyArgv() and _PyCoreConfig_SetWideString() now
pre-initialize Python if needed to ensure that the locale encoding is
properly configured.

* Add _Py_PreInitializeFromPyArgv() internal function.
* Add 'args' parameter to _Py_PreInitializeFromCoreConfig()

_PyCoreConfig: Change filesystem_encoding, filesystem_errors,
stdio_encoding and stdio_errors fields type from char* to wchar_t*.

Changes:

* PyInterpreterState: replace fscodec_initialized (int) with fs_codec
  structure.
* Add get_error_handler_wide() and unicode_encode_utf8() helper
  functions.
* Add error_handler parameter to unicode_encode_locale()
  and unicode_decode_locale().
* Remove _PyCoreConfig_SetString().
* Rename _PyCoreConfig_SetWideString() to _PyCoreConfig_SetString().
* Rename _PyCoreConfig_SetWideStringFromString()
  to _PyCoreConfig_DecodeLocale().

Add private _config_version field to _PyPreConfig and _PyCoreConfig
to prepare future ABI compatibility.

Move get_codec_name() and initfsencoding() from pylifecycle.c to
unicodeobject.c.

Rename also "init" functions in pylifecycle.c.

Add _Py_FORCE_UTF8_LOCALE and _Py_FORCE_UTF8_FS_ENCODING macros to
avoid factorize "#if defined(__ANDROID__) || defined(__VXWORKS__)"
and "#if defined(__APPLE__)".

Cleanup also config_init_fs_encoding().

* Include C14N 2.0 test data in installation.
* Add README file to the C14N test data directory to reference the original source and licensing conditions.

I feel silly even making such a tiny typo fix, but I couldn't help but notice it.

_PyCoreConfig: Rename _check_hash_pycs_mode field to
check_hash_pycs_mode (make it public) and change its type from "const
char*" to "wchar_t*".

This was achieved by:
* moving many pass statements in tests onto their own lines, so they pass line coverage and can match an easy ignore pattern if branch coverage is added later.
* removing code that cannot be reached.
* removing long-disabled tests.
* removing unused code.
* adding tests for uncovered code

It turned out that removing `if __name__ == '__main__'` blocks that run unittest.main() at the bottom of test files was surprisingly contentious, so they remain and can be filtered out with an appropriate .coveragerc.

Use http.client.InvalidURL instead of ValueError as the new error case's exception.

* Implement C14N 2.0 as a new canonicalize() function in ElementTree.

Missing features:
- prefix renaming in XPath expressions (tag and attribute text is supported)
- preservation of original prefixes given redundant namespace declarations

Namespace packages _bootstrap.ModuleSpec.loader attributes are no longer `None` _after_ calling the importlib._bootstrap._init_module_attrs function.

See:
* https://stackoverflow.com/questions/52869541/namespace-package-spec-loader-and-loader-attributes-not-set-to-none
* https://bugs.python.org/issue35181

* bpo-36676: Implement namespace prefix aware parsing support for the XMLParser target in ElementTree.

* bpo-36673: Implement comment/PI parsing support for the TreeBuilder in ElementTree.

* bpo-36673: Rewrite the comment/PI factory handling for the TreeBuilder in "_elementtree" to make it use the same factories as the ElementTree module, and to make it explicit when the comments/PIs are inserted into the tree and when they are not (which is the default).

This is consistent with the rest of the `warnings.warn` usage in the
inspect.py module and aids identifying code that needs to be fixed.

This warning came in via d5d2b454

Add 3 new config methods:

* _PyCoreConfig_SetString()
* _PyCoreConfig_SetWideString()
* _PyCoreConfig_SetWideStringFromString()

Changes:

* _PyCoreConfig_Copy() returns _PyInitError.
* Add CONFIG_GET_ENV_DUP().