anchor.diff:  { stdenv
   , buildPythonPackage
  -, fetchPypi
  +, fetchFromGitHub
   , ansible
   , pytest
   , mock
  
positive.code:   checkInputs =  [ mock ];
    propagatedBuildInputs = [ ansible pytest ];
  
    # tests not included with release
    doCheck = false;
  
    checkPhase = ''
      pytest
    '';
  
    meta = with stdenv.lib; {
  
negative.code: 
  buildPythonPackage rec {
    pname = "pytest-ansible";
    version = "2.1.1";
  
    src = fetchFromGitHub {
      owner = "ansible";
      repo = "pytest-ansible";
      rev = "v${version}";
      sha256 = "0v97sqk3q2vkmwnjlnncz8ss8086x9jg3cz0g2nzlngs4ql1gdb0";
    };
  
    patchPhase = ''
  