anchor.diff: -{ lib, python3, fetchFromGitHub }:
  +{ lib, python3, fetchFromGitHub, fetchurl }:
   let
     python = python3.override {
       # override resolvelib due to
  
positive.code:   #
    # the patch is necessary because the fixture is creating a project and
    # doesn't appear to respect the settings in `$HOME`; possibly a bug upstream
    patches = [ ./check-update.patch ];
  
    propagatedBuildInputs = [
      blinker
  
negative.code:   checkInputs = [
      pytestCheckHook
      pytest-mock
      pytest-xdist
    ];
  
    pytestFlagsArray = [
      "--numprocesses $NIX_BUILD_CORES"
      "-m 'not network'"
    ];
  
    preCheck = "HOME=$TMPDIR";
  
    disabledTests = [
      # sys.executable and expected executable are different
      "test_set_non_exist_python_path"
      # pythonfinder isn't aware of nix's python infrastructure
      "test_auto_isolate_site_packages"
      "test_use_invalid_wrapper_python"
      "test_use_wrapper_python"
      # tries to read/write files without proper permissions
      "test_completion_command"
      "test_plugin_add"
      "test_plugin_list"
      "test_plugin_remove"
      # tries to treat a gzip file as a zipfile and fails
      "test_resolve_local_artifacts"
    ];
  