anchor.diff:  
     virtualenv-clone = buildPythonPackage rec {
       name = "virtualenv-clone-0.2.4";
  -    
  -    src = fetchgit {
  -      url = "https://github.com/berdario/virtualenv-clone.git";
  -      rev = ''c302ca84e524cb22f88c834cccb23dd410cced97'';
  -    };
  -
  +
  +    src = fetchurl {
  +      url = "https://pypi.python.org/packages/source/v/virtualenv-clone/${name}.tar.gz";
  +      md5 = "71168b975eaaa91e65559bcc79290b3b";
  +    };
  +
  +    buildInputs = [pytest];
  +    propagatedBuildInputs = [virtualenv];
  +
  +    # needs tox to run the tests
       doCheck = false;
   
       meta = with stdenv.lib; {
  
positive.code: 
  
    py = buildPythonPackage rec {
      name = "py-1.4.19";
  
      src = fetchurl {
        url = "https://pypi.python.org/packages/source/p/py/${name}.tar.gz";
        md5 = "3857dc8309d5f284669b81184253c2bb";
      };
    };
  
  
negative.code:       md5 = "90a82400074b50a9e73c3045ed9ac217";
      };
  
      propagatedBuildInputs = [ virtualenv virtualenv-clone ];
  
      meta = with stdenv.lib; {
        description = "Tools to manage multiple virtualenvs written in pure python, a virtualenvwrapper rewrite";
  