anchor.diff:    version = "3.9.2";
     name = "mercurial-${version}";
     inherit (python2Packages) docutils hg-git dulwich python;
  -in
  -
  -stdenv.mkDerivation {
  +in python2Packages.mkPythonDerivation {
     inherit name;
   
     src = fetchurl {
  
positive.code: 
    inherit python; # pass it so that the same version can be used in hg2git
  
    buildInputs = [ python makeWrapper docutils unzip ];
  
    propagatedBuildInputs = stdenv.lib.optionals stdenv.isDarwin
      [ ApplicationServices cf-private ];
  
    makeFlags = "PREFIX=$(out)";
  
  
negative.code:     ''
        for i in $(cd $out/bin && ls); do
          wrapProgram $out/bin/$i \
            $WRAP_TK
        done
  
  