nix/doc/manual/rl-next/git-fetcher.md

synopsis	prs	issues
Nix now uses `libgit2` for Git fetching	9240 9241 9258 9480	5313

Nix has built-in support for fetching sources from Git, during evaluation and locking; outside the sandbox. The existing implementation based on the Git CLI had issues regarding reproducibility and performance.

Most of the original fetchGit behavior has been implemented using the libgit2 library, which gives the fetcher fine-grained control.

Known issues:

• The export-subst behavior has not been reimplemented. Partial support for this Git feature is feasible, but it did not make the release window.