nixpkgs/pkgs/applications/version-management/gitlab
..
bootstrap.nix
default.nix
Gemfile.lock
Gemfile.nix
generate_nix_requirements.rb
README
remove-hardcoded-locations.patch

to regenerate Gemfile.nix and Gemfile.lock you need to

  % nix-build bootstrap.nix
  % cp result/Gemfile.nix ./
  % cp result/Gemfile.lock ./