anchor.diff:      robustcheckout = ${hg_tools}/hgext/robustcheckout/__init__.py
       EOF
     '';
  -})
  +}
  
positive.code:     };
    };
  
  
  in mercurial.overrideDerivation (old: {
    postInstall = old.postInstall + ''
      mkdir -p $out/etc/mercurial
      cat > $out/etc/mercurial/hgrc <<EOF
      [web]
  
negative.code: { releng_pkgs }:
  
  let
    inherit (releng_pkgs.pkgs) fetchurl mercurial cacert python2Packages makeWrapper docutils unzip;
    inherit (releng_pkgs.pkgs.stdenv) mkDerivation;
    inherit (releng_pkgs.pkgs.lib) licenses;
  
    hg_tools = mkDerivation {
      name = "mozilla-hg-tools";
      src = fetchurl {
        url = "https://hg.mozilla.org/hgcustom/version-control-tools/archive/825b151d379c.tar.bz2";
        sha256 = "0l4i3x20irshf4xa2xy64nvqi04wrj2h92bn24v2j72nqmg6379x";
      };
      installPhase = ''
        mkdir -p $out
  