Alex Vandiver

This is good for another review.

Thanks for this, @tagyieh! This looks pretty good, and I appreciate you adding a test. I think my only comment is on the commit message. Please give our [documentation on...

Consider setting [`GIT_OPTIONAL_LOCKS`](https://git-scm.com/docs/git#git-codeGITOPTIONALLOCKScode), which is [new in git 2.15.0](https://github.com/git/git/blob/master/Documentation/RelNotes/2.15.0.txt#L97-L100). Setting it as an environment variable is backward-compatible (unlike [passing `--no-optional-locks`](https://git-scm.com/docs/git#git---no-optional-locks)), and will prevent taking the index lock, which disrupts command-line...