Fix handling of osxkeychain addtional keys (#391)

[pgpx]

Fixes #391

Fix handling of osxkeychain addtional keys (#391)

• git-credential-helper v2.45 < v2.47.0 can output additional garbage bytes after the username.
• git-credential-helper >= v2.46.0 outputs additional capability[] and state keys.

[shcheklein]

hi @pgpx , thanks a lot for addressing and for including tests!

please check the tests - seems mypy / linters are failing.

[pgpx]

@shcheklein - oh sorry, looks ok now!

Note the _strip_garbage_bytes method is somewhat dubious since I'm unsure as to what bytes could be added by older versions of git to the username value. I've only ever seen a series of 0-bytes, and so have assumed that everything from the first 0-byte could be discarded since a 0-byte should never be part of a username. However, you could drop that call entirely if you wanted, because git v2.47.0 no longer has that problem anyway (only 2.45.0 - 2.46.0, maybe 2.46.1,2 are affected)

[shcheklein]

thanks, I think that's fine - let's keep it for now

[shcheklein]

thanks @pgpx !