anchor.diff:    src = fetchFromGitHub {
       owner = "sampsyo";
       repo = "beets";
  -    rev = "10d7a6f46ac58d40bc12661d943d2e3ae24761cd";
  -    sha256 = "0e978aa1ccf49b18a6a1914199c8b3110efcaa2c52bc6682c214e0f2fcd0fa7a";
  +    rev = "4c4d8cff60b574296194075bce54a05d017f053b";
  +    sha256 = "90dbbdd1fc3912bb3cefa247ab6b45971ae477d3c099a23aa05e04512a89a27c";
     };
   
     nativeBuildInputs = [
  
positive.code:     werkzeug
    ] ++ optionals isPy27 [
      enum34
    ] ++ optionals (versionOlder pythonPackages.python.versionMajor "3.5") [
      pathlib
    ] ++ [
      pycountry
  
negative.code:   testShell = "${bash}/bin/bash --norc";
    completion = "${bash-completion}/share/bash-completion/bash_completion";
  
    version = "2016-08-18";
  in
  buildPythonPackage rec {
    name = "beets-${version}";
  