anchor.diff:  
   
     pycurl = buildPythonPackage (rec {
  -    name = "pycurl-7.19.0";
  +    name = "pycurl-7.19.5";
   
       src = fetchurl {
         url = "http://pycurl.sourceforge.net/download/${name}.tar.gz";
  -      sha256 = "0hh6icdbp7svcq0p57zf520ifzhn7jw64x07k99j7h57qpy2sy7b";
  +      sha256 = "0hqsap82zklhi5fxhc69kxrwzb0g9566f7sdpz7f9gyxkmyam839";
       };
   
       buildInputs = [ pkgs.curl ];
  
positive.code:   rope = buildPythonPackage rec {
      version = "0.9.4";
      name = "rope-${version}";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/r/rope/${name}.tar.gz";
  
negative.code:   netlib = buildPythonPackage rec {
      baseName = "netlib";
      name = "${baseName}-${meta.version}";
      disabled = (!isPy27);
  
      src = fetchurl {
        url = "https://github.com/cortesi/netlib/archive/v${meta.version}.tar.gz";
  