anchor.diff:      downloadPage = "http://mercurial.selenic.com/release/";
       license = stdenv.lib.licenses.gpl2;
       maintainers = [ stdenv.lib.maintainers.eelco ];
  +    updateWalker = true;
     };
   }
  
positive.code: 
  let
    # if you bump version, update pkgs.tortoisehg too or ping maintainer
    version = "3.7.3";
    name = "mercurial-${version}";
  in
  
  
negative.code: 
    src = fetchurl {
      url = "http://mercurial.selenic.com/release/${name}.tar.gz";
      sha256 = "156m6269xdqq7mpw01c6b065k29xnb8b9lyzn1b0nlz5il2izkps";
    };
  
    inherit python; # pass it so that the same version can be used in hg2git
  