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

shutil.py の 1311 行付近から始め、レポートに示されている欠落ファイルとアクセスできないパスのコマンドを再現します。既存の unpack_archive の動作と、存在する場合は関連するテストを確認します。完了条件は、これらの入力が汎用的な ReadError ではなく、詳細なファイルシステム例外を公開することです。