Flake operations fail in repositories using Git split-index

[eigengrau]

Describe the bug

Certain Nix Flake operations will fail when a repository uses Git’s split-index feature.

This is most likely an upstream issue, cf. libgit2/libgit2#6132. Not sure if you want to keep the issue around, here, as well. Feel free to close.

Steps To Reproduce

git init $TMPDIR/example
cd $TMPDIR/example
git config --local core.splitIndex yes
nix flake init
nix flake update

Observe that this results in:

error: getting working directory status: unsupported mandatory extension: 'link'

Expected behavior

nix flake update succeeds

nix-env --version output

nix-env (Nix) 2.24.9