Add an option to the preferences drop down menu to restart calibre without third party plugins. Fixes #1944057 [[Enhancement] Additional option for Preference](https://bugs.launchpad.net/calibre/+bug/1944057)

src/calibre/gui2/actions/preferences.py

@@ -36,6 +36,9 @@ class PreferencesAction(InterfaceAction):
             pm.addSeparator()
             cm('restart', _('Restart in debug mode'), icon='debug.png',
                     triggered=self.debug_restart, shortcut='Ctrl+Shift+R')
+        pm.addSeparator()
+        cm('restart_without_plugins', _('Restart ignoring third party plugins'), icon='debug.png',
+            triggered=self.no_plugins_restart, shortcut='Ctrl+Alt+Shift+R')
 
         self.preferences_menu = pm
         for x in (self.gui.preferences_action, self.qaction):
@@ -72,3 +75,6 @@ class PreferencesAction(InterfaceAction):
 
     def debug_restart(self, *args):
         self.gui.quit(restart=True, debug_on_restart=True)
+
+    def no_plugins_restart(self, *args):
+        self.gui.quit(restart=True, no_plugins_on_restart=True)

src/calibre/gui2/main.py

@@ -29,7 +29,7 @@ from calibre.utils.lock import SingleInstance
 from calibre.utils.monotonic import monotonic
 from polyglot.builtins import as_bytes, environ_item, range, unicode_type
 
-after_quit_actions = {'debug_on_restart': False, 'restart_after_quit': False}
+after_quit_actions = {'debug_on_restart': False, 'restart_after_quit': False, 'no_plugins_on_restart': False}
 if iswindows:
     from calibre_extensions import winutil
 
@@ -110,6 +110,8 @@ def find_portable_library():
 def init_qt(args):
     parser = option_parser()
     opts, args = parser.parse_args(args)
+    if os.environ.pop('CALIBRE_IGNORE_PLUGINS_ON_RESTART', '') == '1':
+        opts.ignore_plugins = True
     find_portable_library()
     if opts.with_library is not None:
         libpath = os.path.expanduser(opts.with_library)
@@ -421,6 +423,7 @@ def run_gui_(opts, args, app, gui_debug=None):
     if getattr(runner.main, 'restart_after_quit', False):
         after_quit_actions['restart_after_quit'] = True
         after_quit_actions['debug_on_restart'] = getattr(runner.main, 'debug_on_restart', False) or gui_debug is not None
+        after_quit_actions['no_plugins_on_restart'] = getattr(runner.main, 'no_plugins_on_restart', False)
     else:
         if iswindows:
             try:
@@ -491,6 +494,8 @@ def restart_after_quit():
     if iswindows and not is_calibre_debug_exe:
         # detach the stdout/stderr/stdin handles
         winutil.prepare_for_restart()
+    if after_quit_actions['no_plugins_on_restart']:
+        os.environ['CALIBRE_IGNORE_PLUGINS_ON_RESTART'] = '1'
     if after_quit_actions['debug_on_restart']:
         run_in_debug_mode()
         return

src/calibre/gui2/ui.py

@@ -1060,7 +1060,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
             self.stack.tb_widget.save_state()
 
     def quit(self, checked=True, restart=False, debug_on_restart=False,
-            confirm_quit=True):
+            confirm_quit=True, no_plugins_on_restart=False):
         if self.shutting_down:
             return
         if confirm_quit and not self.confirm_quit():
@@ -1072,6 +1072,7 @@ class Main(MainWindow, MainWindowMixin, DeviceMixin, EmailMixin,  # {{{
             traceback.print_exc()
         self.restart_after_quit = restart
         self.debug_on_restart = debug_on_restart
+        self.no_plugins_on_restart = no_plugins_on_restart
         if self.system_tray_icon is not None and self.restart_after_quit:
             # Needed on windows to prevent multiple systray icons
             self.system_tray_icon.setVisible(False)