anchor.diff: -{ stdenv, buildPythonPackage, fetchPypi, isPy3k, pythonOlder
  +{ stdenv, lib, buildPythonPackage, fetchPypi, isPy3k, pythonOlder
   , attrs, click, cligj, click-plugins, six, munch, enum34
  -, pytest, boto3, mock
  +, pytest, boto3, mock, giflib
   , gdal_2 # can't bump to 3 yet, https://github.com/Toblerity/Fiona/issues/745
   }:
   
  
positive.code:     click-plugins
      six
      munch
    ] ++ stdenv.lib.optional (!isPy3k) enum34;
  
    checkInputs = [
      pytest
      boto3
    ] ++ stdenv.lib.optional (pythonOlder "3.4") mock;
  
    checkPhase = ''
      rm -r fiona # prevent importing local fiona
  
negative.code: 
    buildInputs = [
      gdal_2
    ] ++ lib.optionals stdenv.cc.isClang [ giflib ];
  
    propagatedBuildInputs = [
      attrs
  