anchor.diff: -{ buildPythonPackage, lib, fetchPypi
  -, pytest_4, filelock, mock, pep8
  -, cython, isPy27
  +{ buildPythonPackage, lib, fetchPypi, fetchpatch
  +, pytestCheckHook, filelock, mock, pep8
  +, cython
   , six, pyshp, shapely, geos, numpy
   , gdal, pillow, matplotlib, pyepsg, pykdtree, scipy, owslib, fiona
  -, xvfb_run
  -, proj_5 # see https://github.com/SciTools/cartopy/pull/1252 for status on proj 6 support
  +, proj
   }:
   
   buildPythonPackage rec {
  
positive.code:     gdal pillow matplotlib pyepsg pykdtree scipy fiona owslib
    ];
  
    meta = with lib; {
      description = "Process geospatial data to create maps and perform analyses";
      license = licenses.lgpl3;
      homepage = "https://scitools.org.uk/cartopy/docs/latest/";
      maintainers = with maintainers; [ mredaelli ];
      # following tests fail: test_eccentric_globe and test_ellipse_globe
      broken = true;
    };
  }
  
negative.code:     sha256 = "0d24fk0cbp29gmkysrwq05vry13swmwi3vx3cpcy04c0ixz33ykz";
    };
  
    patches = [
      # Fix numpy-1.20 compatibility.  Will be part of 0.19.
      (fetchpatch {
        url = "https://github.com/SciTools/cartopy/commit/e663bbbef07989a5f8484a8f36ea9c07e61d14ce.patch";
        sha256 = "061kbjgzkc3apaz6sxy00pkgy3n9dxcgps5wzj4rglb5iy86n2kq";
      })
    ];
  
    buildInputs = [
      geos proj
    ];
  
    propagatedBuildInputs = [
  