anchor.diff:  
     disabled = isPy3k; # see https://github.com/thumbor/thumbor/issues/1004
   
  -  src = fetchPypi {
  -    inherit pname version;
  -    sha256 = "1icfnzwzi5lvnh576n7v3r819jaw15ph9ja2w3fwg5z9qs40xvl8";
  +  # Tests aren't included in PyPI tarball so use GitHub instead
  +  src = fetchFromGitHub {
  +    owner = pname;
  +    repo = pname;
  +    rev = version;
  +    sha256 = "1ys5ymwbvgh2ir85g9nyrzzf8vgi16j6pzzi53b0rgjx0kwlmnxg";
     };
   
     postPatch = ''
       substituteInPlace "setup.py" \
         --replace '"argparse",' "" ${lib.optionalString isPy3k ''--replace '"futures",' ""''}
  +    substituteInPlace "tests/test_utils.py" \
  +      --replace "/bin/ls" "${coreutils}/bin/ls"
  +    substituteInPlace "tests/detectors/test_face_detector.py" \
  +      --replace "./thumbor" "$out/lib/${python.libPrefix}/site-packages/thumbor"
  +    substituteInPlace "tests/detectors/test_glasses_detector.py" \
  +      --replace "./thumbor" "$out/lib/${python.libPrefix}/site-packages/thumbor"
     '';
  +
  +  checkInputs = [
  +    nose
  +    pyssim
  +    preggy
  +    mock
  +    yanc
  +    remotecv
  +    cairosvg1
  +    raven
  +    pkgs.redis
  +    pkgs.glibcLocales
  +  ];
   
     propagatedBuildInputs = [
       tornado
  
positive.code:     pillow
      derpconf
      python_magic
      pexif
      libthumbor
      opencv
      webcolors
      piexif
      statsd
    ] ++ lib.optionals (!isPy3k) [ futures thumborPexif ];
  
    # disabled due to too many impure tests and issues with native modules in
    # the pure testing environment. See https://github.com/NixOS/nixpkgs/pull/37147
    # for further reference.
    doCheck = false;
  
    meta = with lib; {
      description = "A smart imaging service";
  
negative.code: { buildPythonPackage, python, tornado, pycrypto, pycurl, pytz
  , pillow, derpconf, python_magic, libthumbor, webcolors
  , piexif, futures, statsd, thumborPexif, fetchFromGitHub, isPy3k, lib
  , mock, raven, nose, yanc, remotecv, pyssim, cairosvg1, preggy, opencv3
  , pkgs, coreutils
  }:
  
  buildPythonPackage rec {
  