anchor.diff:  
   python3Packages.buildPythonApplication rec {
     pname = "xonsh";
  -  version = "0.9.24";
  +  version = "0.9.27";
   
     # fetch from github because the pypi package ships incomplete tests
     src = fetchFromGitHub {
       owner  = "xonsh";
       repo   = "xonsh";
       rev    = version;
  -    sha256 = "1nk7kbiv7jzmr6narsnr0nyzkhlc7xw3b2bksyq2j6nda67b9b3y";
  +    sha256 = "09w6bl3qsygfs2ph2r423ndnbd74bzf67vp8587h2dkkfxlzjbad";
     };
   
     LC_ALL = "en_US.UTF-8";
  
positive.code:   meta = with lib; {
      description = "A Python-ish, BASHwards-compatible shell";
      homepage = "https://xon.sh/";
      changelog = "https://github.com/xonsh/xonsh/releases/tag/${version}";
      license = licenses.bsd3;
      maintainers = with maintainers; [ spwhitt vrthra ];
      platforms = platforms.all;
  
negative.code:   doCheck = !stdenv.isDarwin;
  
    checkPhase = ''
      HOME=$TMPDIR pytest -k 'not test_repath_backslash and not test_os and not test_man_completion and not test_builtins and not test_main and not test_ptk_highlight and not test_pyghooks and not test_command_pipeline_capture and not test_git_dirty_working_directory_includes_untracked and not test_dirty_working_directory and not test_vc_get_branch'
      HOME=$TMPDIR pytest -k 'test_builtins or test_main' --reruns 5
      HOME=$TMPDIR pytest -k 'test_ptk_highlight'
    '';
  