addressee: Accept a realm object in legacy_build.

This fixes a bug where the internal_prep_message code path would
incorrectly ignore the `realm` that was passed into it.  As a result,
attempts to send messages using the system bots with this code path
would crash.

As a sidenote, we really need to make our test system consistent with
production in terms of whether the user's realm is the same as the
system realm.

zerver/lib/actions.py

@@ -1643,7 +1643,8 @@ def internal_prep_message(realm, sender_email, recipient_type_name, recipients,
         sender,
         recipient_type_name,
         parsed_recipients,
-        subject)
+        subject,
+        realm=realm)
 
     return _internal_prep_message(
         realm=realm,

zerver/lib/addressee.py

@@ -80,12 +80,15 @@ class Addressee(object):
         return self._topic
 
     @staticmethod
-    def legacy_build(sender, message_type_name, message_to, topic_name):
-        # type: (UserProfile, Text, Sequence[Text], Text) -> Addressee
+    def legacy_build(sender, message_type_name, message_to, topic_name, realm=None):
+        # type: (UserProfile, Text, Sequence[Text], Text, Optional[Realm]) -> Addressee
 
         # For legacy reason message_to used to be either a list of
         # emails or a list of streams.  We haven't fixed all of our
         # callers yet.
+        if realm is None:
+            realm = sender.realm
+
         if message_type_name == 'stream':
             if len(message_to) > 1:
                 raise JsonableError(_("Cannot send to multiple streams"))
@@ -101,7 +104,7 @@ class Addressee(object):
             return Addressee.for_stream(stream_name, topic_name)
         elif message_type_name == 'private':
             emails = message_to
-            return Addressee.for_private(emails, sender.realm)
+            return Addressee.for_private(emails, realm)
         else:
             raise JsonableError(_("Invalid message type"))