Turn flush_realm() into a post-save hook for Realm.

(imported from commit 97e44b51e2b35b4b5b64b4008f6a8d3585a26e33)

zerver/lib/actions.py

@@ -3,7 +3,7 @@ from __future__ import absolute_import
 from django.conf import settings
 from django.core import validators
 from django.contrib.sessions.models import Session
-from zerver.lib.cache import flush_user_profile, flush_realm
+from zerver.lib.cache import flush_user_profile
 from zerver.lib.context_managers import lockfile
 from zerver.models import Realm, RealmEmoji, Stream, UserProfile, UserActivity, \
     Subscription, Recipient, Message, UserMessage, valid_stream_name, \
@@ -167,8 +167,6 @@ def do_deactivate_realm(realm):
         # notice when they try to log in.
         delete_user_sessions(user)
 
-    flush_realm(realm)
-
 def do_deactivate_user(user_profile, log=True, _cascade=True):
     if not user_profile.is_active:
         return