crystfel: more review fixes

    src = fetchFromGitHub {

      owner = "nexusformat";

      repo = pname;

      rev = "master";

      rev = "49e3b65eca772bca77af13ba047d8b577673afba";

      hash = "sha256-bEzfWdZuHmb0PDzCqy8Dey4tLtq+4coO0sT0GzqrTYI=";

    };