anchor.diff:    meta = with lib; {
       description = "A Python-ish, BASHwards-compatible shell";
       homepage = "https://xon.sh/";
  -    changelog = "https://github.com/xonsh/xonsh/releases/tag/${version}";
  +    changelog = "https://github.com/xonsh/xonsh/raw/${version}/CHANGELOG.rst";
       license = licenses.bsd3;
       maintainers = with maintainers; [ spwhitt vrthra ];
       platforms = platforms.all;
  
positive.code:   doCheck = !stdenv.isDarwin;
  
    checkPhase = ''
      HOME=$TMPDIR pytest -k 'not test_repath_backslash and not test_os and not test_man_completion and not test_builtins and not test_main and not test_ptk_highlight and not test_pyghooks'
      HOME=$TMPDIR pytest -k 'test_builtins or test_main' --reruns 5
      HOME=$TMPDIR pytest -k 'test_ptk_highlight'
    '';
  
negative.code: 
  python3Packages.buildPythonApplication rec {
    pname = "xonsh";
    version = "0.9.27";
  
    # fetch from github because the pypi package ships incomplete tests
    src = fetchFromGitHub {
      owner  = "xonsh";
      repo   = "xonsh";
      rev    = version;
      sha256 = "09w6bl3qsygfs2ph2r423ndnbd74bzf67vp8587h2dkkfxlzjbad";
    };
  
    LC_ALL = "en_US.UTF-8";
  