fetchgit: install git LFS with --local

[panicgh]

Motivation for this change

nix-builders run with GIT_CONFIG_NOSYSTEM (#63774) and git lfs install fails. The approach taken in PR #105998 sets HOME=$TMPDIR to make it work. However, git lfs install supports a --local flag to set itself up in the local repository's git config. I believe this would be cleaner than the current approach. Furthermore, nix-prefetch-git lacks the git-lfs dependence and does not publicly document the command line switch --fetch-lfs.

Note: I suspect this PR could cause git-lfs files in submodules not be fetched, so it may still need minor refinement.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[r-rmcgibbo]

Result of nixpkgs-review pr 113580 at e51cf7b5 run on aarch64-linux 1

11 packages built:

• bundix
• cabal2nix
• crate2nix
• dep2nix
• go2nix
• haskellPackages.update-nix-fetchgit
• nix-prefetch-git
• nix-prefetch-scripts
• nix-update-source
• update-nix-fetchgit
• vgo2nix

2 suggestions:

• warning: license-missing

  Package is missing a license

  Near pkgs/tools/package-management/nix-prefetch-scripts/default.nix:22:5:

     |
  22 |     meta = with lib; {
     |     ^
  

• warning: missing-phase-hooks

  installPhase should probably contain runHook preInstall and runHook postInstall.

  Near pkgs/tools/package-management/nix-prefetch-scripts/default.nix:13:5:

     |
  13 |     installPhase = ''
     |     ^
  

[bjornfor]

This is much better than the current situation: I'm having problems using nix-prefetch-git --fetch-lfs at all (on current master). I think we should (rebase and) merge.

[bjornfor]

I tested this on top of master, success! Keep in mind that --fetch-lfs CLI flag has been added already, and git doesn't catch that as a conflict, so I ended up with two --fetch-lfs in the help output :-)

The only thing I think we should add is

diff --git a/pkgs/build-support/fetchgit/nix-prefetch-git b/pkgs/build-support/fetchgit/nix-prefetch-git
index 879f187994e..30b046abdd3 100755
--- a/pkgs/build-support/fetchgit/nix-prefetch-git
+++ b/pkgs/build-support/fetchgit/nix-prefetch-git
@@ -403,6 +403,7 @@ print_results() {
   "date": "$(json_escape "$commitDateStrict8601")",
   "path": "$(json_escape "$finalPath")",
   "$(json_escape "$hashType")": "$(json_escape "$hash")",
+  "fetchLFS": $([[ -n "$fetchLFS" ]] && echo true || echo false),
   "fetchSubmodules": $([[ -n "$fetchSubmodules" ]] && echo true || echo false),
   "deepClone": $([[ -n "$deepClone" ]] && echo true || echo false),
   "leaveDotGit": $([[ -n "$leaveDotGit" ]] && echo true || echo false)

[bjornfor]

Note: I suspect this PR could cause git-lfs files in submodules not be fetched, so it may still need minor refinement.

Oh, I see. I'll try to test it.

[bjornfor]

Sorry, I haven't had time to test this wrt. git submodules, but I created this PR (#134122) now to at least make nix-prefetch-git --fetch-lfs work out of the box.