bpo-42112: ZipInfo.from_file removes only needed slashes

[matan1008]

https://bugs.python.org/issue42112

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[github-actions]

This PR is stale because it has been open for 30 days with no activity.

[MaxwellDupre]

Everything looks ok; all tests pass. But there is zero documentation, not here, not in the original issue. Could you add some description please, possibly a test case? Also, don't see any test for this change, could add please?

[matan1008]

I added a test case in 348a679
And explained the issue in 30b5e4d
Since I am pretty new to submitting PRs to python, could you please be more specific?

[MaxwellDupre]

Ah yes I see it now:
test_reading_archive_member_starts_with_slash (test.test_zipfile.OtherTests) ... ok
Your changes are in from_file but the test is in Other.Tests
Is there a reason for that?

Ok, but the info for this change in minimalist in the extreme.

[github-actions]

This PR is stale because it has been open for 30 days with no activity.