shutil.unpack_archive returns bogus ReadError exceptions when input is not found or inaccessible

Bug report

$ python -c 'import shutil; shutil.unpack_archive("./enoent")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python3.11/shutil.py", line 1311, in unpack_archive
    raise ReadError("Unknown archive format '{0}'".format(filename))
shutil.ReadError: Unknown archive format './enoent'

$ python -c 'import shutil; shutil.unpack_archive("/root/inaccessible")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib64/python3.11/shutil.py", line 1311, in unpack_archive
    raise ReadError("Unknown archive format '{0}'".format(filename))
shutil.ReadError: Unknown archive format '/root/inaccessible'

The generic exception makes it handle to handle the error programatically, and the message is also very confusing to the user. Instead, the function should just propagate the detailed exception it got internally. Compare with open:

$ python -c 'open("./enoent")'
Traceback (most recent call last):
  File "<string>", line 1, in <module>
FileNotFoundError: [Errno 2] No such file or directory: './enoent'

$ python -c 'open("/root/inaccessible")' 
Traceback (most recent call last):
  File "<string>", line 1, in <module>
PermissionError: [Errno 13] Permission denied: '/root/inaccessible'

Your environment

python3-3.11.0-1.fc37.x86_64

Linked PRs

• gh-155587

从 shutil.py 第 1311 行附近开始，重现报告中所示的缺失文件和无法访问路径的命令。检查现有的 unpack_archive 行为以及相关测试（如果有）；完成的标准是这些输入会暴露其详细的文件系统异常，而不是通用的 ReadError。