anchor.diff:        owner = "marco-c";
         repo = "grcov";
         rev = "v${version}";
  -      sha256 = "1b43pdi00bkpa7pii2hnasml208581ygmspqr7gpq186k7cil8x0";
  +      sha256 = "12lkzfh2iwxxyzy29rjjd6q3zvkpb6kw3v367xmckf1vabh7p3yp";
       };
   
   	# ...
  
positive.code: let
  
    inherit (releng_pkgs.lib) mkTaskclusterHook mkTaskclusterMergeEnv mkPython fromRequirementsFile filterSource mkRustPlatform;
    inherit (releng_pkgs.pkgs) writeScript makeWrapper fetchurl cacert git llvm_7 libxml2;
    inherit (releng_pkgs.pkgs.stdenv) mkDerivation;
    inherit (releng_pkgs.pkgs.lib) fileContents optional licenses;
    inherit (releng_pkgs.tools) pypi2nix mercurial ;
  
negative.code: 
    # Marco grcov
    grcov = rustPlatform.buildRustPackage rec {
      version = "0.4.0";
      name = "grcov-${version}";
  
      buildInputs = [
          libxml2
      ];
  
  