anchor.diff:  
     billiard = buildPythonPackage rec {
       name = "billiard-${version}";
  -    version = "3.3.0.19";
  +    version = "3.3.0.21";
   
       disabled = isPyPy;
   
       src = pkgs.fetchurl {
         url = "https://pypi.python.org/packages/source/b/billiard/${name}.tar.gz";
  -      sha256 = "06bs1kl7dji6lwpj3dkfi61mmrfq2mi7wz3ka683i2avwk38wsvf";
  -      md5 = "7e473b9da01956ce91a650f99fe8d4ad";
  +      sha256 = "1sfsrkm5xv820wp2mz5zn2rnw6s0c9wal69v1fkr26wp1a7zf1cp";
       };
   
       buildInputs = with self; [ nose unittest2 mock ];
  
positive.code: 
    kombu = buildPythonPackage rec {
      name = "kombu-${version}";
      version = "3.0.28";
  
      disabled = pythonOlder "2.6";
  
      src = pkgs.fetchurl {
        url = "https://pypi.python.org/packages/source/k/kombu/${name}.tar.gz";
        sha256 = "1c8sdgfbv1gscc5d14xa3r48qfpppb0vifc9nx0p9fvv9rfg6an2";
      };
  
      buildInputs = with self; optionals (!isPy3k) [ anyjson mock unittest2 nose ];
  
negative.code: 
    celery = buildPythonPackage rec {
      name = "celery-${version}";
      version = "3.1.19";
  
      disabled = pythonOlder "2.6";
  
      src = pkgs.fetchurl {
        url = "https://pypi.python.org/packages/source/c/celery/${name}.tar.gz";
        sha256 = "0wbbsrg3vfq8v7y2nylal1gqmn3h4a5vqzbsjiwcybl21hlj2smx";
      };
  
      buildInputs = with self; [ mock nose unittest2 ];
  