Code cleanup withe left overs from old plugin manager removed.

tests/test_plugin_system_manager_regressions.py

@@ -137,6 +137,21 @@ class PluginSystemManagerRegressionTests(unittest.TestCase):
             self.assertEqual(instance.deactivation_count, 1)
             self.assertEqual(plugin_info.instance, None)
 
+    @mock.patch("cthulhu.plugin_system_manager.dbus_service.get_remote_controller")
+    def test_obsolete_plugin_manager_active_entry_is_dropped(self, remote_controller):
+        remote_controller.return_value = mock.Mock()
+
+        with tempfile.TemporaryDirectory() as temp_dir:
+            manager = self._create_manager()
+            plugin_info = self._create_plugin_info(temp_dir, "OCR")
+            manager._plugins["OCR"] = plugin_info
+            manager._plugin_name_index["OCR"] = ["OCR"]
+
+            with mock.patch.object(manager, "syncAllPluginsActive"):
+                manager.setActivePlugins(["PluginManager", "OCR"])
+
+            self.assertEqual(manager.getActivePlugins(), ["OCR"])
+
 
 if __name__ == "__main__":
     unittest.main()