anchor.diff:  # This is an updater for unstable packages that should always use the latest
   # commit.
   { url ? null # The git url, if empty it will be set to src.url
  +, branch ? null
   }:
   
   let
  
positive.code: 
      # Get info about HEAD from a shallow git clone
      tmpdir="$(${coreutils}/bin/mktemp -d)"
      ${git}/bin/git clone --bare --depth=1 "$url" "$tmpdir"
      pushd "$tmpdir"
      commit_date="$(${git}/bin/git show -s --pretty='format:%cs')"
      commit_sha="$(${git}/bin/git show -s --pretty='format:%H')"
  
negative.code: { lib
  , writeShellScript
  , coreutils
  , git
  , nix
  