--- manager.py	2018-11-07 03:51:22.764685289 -0800
+++ manager.py.new	2018-11-07 03:58:21.014139558 -0800
@@ -314,8 +314,7 @@
         if self._events is None:
             # NOTE(danms): We really should have a more specific error
             # here, but this is what we use for our default error case
-            raise exception.NovaException('In shutdown, no new events '
-                                          'can be scheduled')
+            self._events = {}

         @utils.synchronized(self._lock_name(instance))
         def _create_or_get_event():