Non-roundtrip push to josh branch when a commit has a `.` as the last character of the author name

[RalfJung]

The commit rust-lang/rust-analyzer@5af51fa does not properly round-trip through a push to josh.

Original commit info (git show --format=raw):

commit 5af51fa47610d0f88dcab99aaaff2ee4fca17c00
tree 5cf661188e20157ffab5d742ce22d5fa44d18bd1
parent 4a91453409aaf58eba0a91e4b62a35f49814b394
author Winston H. <56998716+winstxnhdw@users.noreply.github.com> 1721814140 +0100
committer GitHub <noreply@github.com> 1721814140 +0100

After a round-trip through josh:

commit fc919994d0759bca7423444e0d0bc044df80359a
tree 5cf661188e20157ffab5d742ce22d5fa44d18bd1
parent 4a91453409aaf58eba0a91e4b62a35f49814b394
author Winston H <56998716+winstxnhdw@users.noreply.github.com> 1721814140 +0100
committer GitHub <noreply@github.com> 1721814140 +0100

The . after Winston H went missing. Seems like somewhere josh is normalizing usernames and doesn't like the trailing .?

[RalfJung]

Seems like git used to prevent a . from even existing at the end of a username, but this got changed last year. So probably whatever git library josh is using needs to get the same kind of update?

[RalfJung]

This change was mirrored in libgit2 via libgit2/libgit2@cf320cc, which was included in libgit2 1.8. That needs version 0.19 of the git2 Rust crate.