From f60c9e2a01598c1900ab785096aa379d1fb6ac5b Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 6 Sep 2018 17:01:41 +0100
Subject: [PATCH] Don't send empty tags list down sync

---
 synapse/handlers/sync.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index 150d492cb0..7eed2fcc9b 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -1583,6 +1583,11 @@ class SyncHandler(object):
             user_id = sync_result_builder.sync_config.user.to_string()
             tags = yield self.store.get_tags_for_room(user_id, room_id)
 
+            # If there aren't any tags, don't send the empty tags list down
+            # sync
+            if not tags:
+                tags = None
+
         account_data_events = []
         if tags is not None:
             account_data_events.append({