Given a zipfile with the following content:

subdir/
file1.txt
subdir/file2.txt

    >>> archive = ZipFile(file_path, "r")
    >>> f = archive.open("subdir/", "r")
    >>>f.read()
    b''

It is quite odd that the subdirectory can be opened as if it was an empty file.  One would expect it to raise.

One use case is that the archive is created using shutil.make_archive, which includes the subdirectory paths in the namelist.  Upon looping ZipFile.namelist(), you end up opening a subdirectory and getting the empty content, which should have led to error and prompted the developers to filter the namelist first.