anchor.diff:  { lib
   , buildPythonPackage
  -, fetchPypi
  +, fetchFromGitHub
   , fetchpatch
   , pyparsing
   , numpy
   , cython
   , astropy
   , astropy-helpers
  -, pytest
  +, pytestCheckHook
   , pytest-astropy
   }:
   
  
positive.code:   '';
  
    # Tests must be run in the build directory
    checkPhase = ''
      cd build/lib.*
      pytest
    '';
  
    meta = with lib; {
  
negative.code:   pname = "pyregion";
    version = "2.0";
  
    # pypi src contains cython-produced .c files which don't compile
    # with python3.9
    src = fetchFromGitHub {
      owner = "astropy";
      repo = pname;
      rev = version;
      sha256 = "1izar7z606czcyws9s8bjbpb1xhqshpv5009rlpc92hciw7jv4kg";
    };
  
    propagatedBuildInputs = [
      pyparsing
      numpy
      astropy
    ];
  
  