emails: Show realm_str inside bracket in subject.

templates/zerver/emails/missed_message.subject.txt

@@ -6,5 +6,5 @@
 {% else %}
     New missed messages
 {% endif %}
-{% if realm_name_in_notifications %} in {{ realm_str }}
+{% if realm_name_in_notifications %} [{{ realm_str }}]
 {% endif %}

version.py

@@ -21,4 +21,4 @@ LATEST_RELEASE_ANNOUNCEMENT = "https://blog.zulip.org/2019/03/01/zulip-2-0-relea
 # Typically, adding a dependency only requires a minor version bump, and
 # removing a dependency requires a major version bump.
 
-PROVISION_VERSION = '37.2'
+PROVISION_VERSION = '37.3'

zerver/tests/test_email_notifications.py

@@ -221,7 +221,7 @@ class TestMissedMessages(ZulipTestCase):
         email_subject = 'PMs with Othello, the Moor of Venice'
 
         if realm_name_in_notifications:
-            email_subject = 'PMs with Othello, the Moor of Venice in Zulip Dev'
+            email_subject = 'PMs with Othello, the Moor of Venice [Zulip Dev]'
         self._test_cases(tokens, msg_id, body, email_subject, False)
 
     @patch('zerver.lib.email_mirror.generate_random_token')