anchor.diff: -{ stdenv
  +{ lib
   , buildPythonPackage
   , fetchPypi
  -, unittest2
  +, isPy27
   , funcsigs
   , six
   , pbr
  
positive.code:     ${python.interpreter} -m unittest discover
    '';
  
    meta = with stdenv.lib; {
      description = "Mock objects for Python";
      homepage = http://python-mock.sourceforge.net/;
      license = stdenv.lib.licenses.bsd2;
    };
  
  }
  
negative.code:     sha256 = "83657d894c90d5681d62155c82bda9c1187827525880eda8ff5df4ec813437c3";
    };
  
    propagatedBuildInputs = [ six pbr ] ++ lib.optionals isPy27 [ funcsigs ];
  
    # On PyPy for Python 2.7 in particular, Mock's tests have a known failure.
    # Mock upstream has a decoration to disable the failing test and make
  