Fetch Git LFS objects

[hacker1024]

This PR changes the Git input plugin to fetch LFS objects alongside the regular git fetch when creating SCM caches. This allows the objects to be used in subsequent clones from the cache (done automatically when programs.git-lfs.enable is true).

This is harmless for repositories that do not use LFS.

Related: #824 (I'm not sure how this affects flakes).

[DerDennisOP]

@NixOS/hydra-maintainers could someone please merge this?

[Daholli]

I just came across this very issue, I recently started building my system configs with hydra

https://hydra.christophhollizeck.dev/build/192#tabs-summary
this build succeeded and using nix-serve I presumably got everything I needed, but when I rebuilt the system both images I have in my lfs that are put in the nix store using homemanagers file.source were missing but referenced

and since my system believes that it got everything properly from the cache it does not rebuild even tho there are files missing in the store

gitattributes

*.png filter=lfs diff=lfs merge=lfs -text
*.webp filter=lfs diff=lfs merge=lfs -text
*.jpg filter=lfs diff=lfs merge=lfs -text

how i put the files into the nix store

home.file = {
  "Pictures/firewatch.jpg".source = ./firewatch.jpg;
};