Publicly expose `shutil.ReadError` and `shutil.RegistryError`

Bug report

Bug description

shutil.ReadError and shutil.RegistryError are not included in shutil.__all__, making them inaccessible via wildcard import. Both exceptions are actively raised by public API functions:

• ReadError is raised by unpack_archive()
• RegistryError is raised by register_unpack_format()

The other shutil exceptions (Error, SameFileError, SpecialFileError) are all in __all__.

>>> from shutil import *
>>> try:
...     unpack_archive("nonexistent.zip")
... except ReadError:
...     pass
...
NameError: name 'ReadError' is not defined. Did you mean: 'KeyError'?

Impact

• from shutil import * does not export ReadError or RegistryError, so users cannot catch exceptions raised by unpack_archive() or register_unpack_format() without explicitly importing them by name.
• Neither exception is documented in Doc/library/shutil.rst, while the other three shutil exceptions (Error, SameFileError, SpecialFileError) all have dedicated .. exception:: entries.
• Tools that rely on __all__ for API discovery (linters, IDE autocompletion, documentation generators) will not surface these exceptions.

This was introduced in commit 6ac91723bd7 (bpo-8295, 2010) which added the archive functions and exceptions but did not add ReadError or RegistryError to __all__. A later fix for incomplete __all__ (#66855, 2014) added SameFileError but missed these two.

Verified on Python 3.14.3 in a clean venv.

Proposed fix

Add "ReadError" and "RegistryError" to __all__ in Lib/shutil.py, and add .. exception:: entries in Doc/library/shutil.rst to document them alongside the other exceptions.

CPython versions tested on:

3.14

Operating system:

All

Linked PRs

• gh-148004

Kiểm tra all trong Lib/shutil.py và các mục ngoại lệ trong Doc/library/shutil.rst, sau đó xem xét PR được liên kết gh-148004 trước khi bắt đầu. Xác minh rằng cả hai ngoại lệ đều được cung cấp thông qua wildcard import và được ghi lại cùng với các ngoại lệ shutil khác.