anchor.diff:    rustPlatform = mkRustPlatform {};
     name = "mozilla-shipit-code-coverage";
     dirname = "shipit_code_coverage";
  +
  +  robustcheckout = mkDerivation {
  +    name = "robustcheckout";
  +    src = fetchurl {
  +      url = "https://hg.mozilla.org/hgcustom/version-control-tools/archive/1a8415be17e8.tar.bz2";
  +      sha256 = "005n7ar8cn7162s1qx970x1aabv263zp7mxm38byxc23nzym37kn";
  +    };
  +    installPhase = ''
  +      mkdir -p $out
  +      cp -rf hgext/robustcheckout $out
  +    '';
  +    doCheck = false;
  +    buildInputs = [];
  +    propagatedBuildInputs = [ ];
  +    meta = {
  +      homepage = "https://hg.mozilla.org/hgcustom/version-control-tools";
  +      license = licenses.mit;
  +      description = "Mozilla Version Control Tools: robustcheckout";
  +    };
  +  };
   
     mercurial' = mercurial.overrideDerivation (old: {
       postInstall = old.postInstall + ''
  
positive.code:       ln -s ${rustStable.rustc}/bin/rustc $out/bin
        ln -s ${rustStable.cargo}/bin/cargo $out/bin
      '';
      passthru = {
        taskclusterHooks = {
          master = {
  
negative.code: 
  [extensions]
  purge =
  robustcheckout = ${robustcheckout}/robustcheckout/__init__.py
  EOF
      '';
    });
  