From 4a94eb3ea40a3c1bee5916d57f5c72bb75c28cf3 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Fri, 15 Sep 2017 09:56:54 +0100
Subject: [PATCH] Fix typo

---
 synapse/handlers/device.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index ac9868d81..0d6750f0e 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -338,7 +338,7 @@ class DeviceHandler(BaseHandler):
                         etype, state_key = key
                         if etype != EventTypes.Member:
                             continue
-                        possibly_changed.append(state_key)
+                        possibly_changed.add(state_key)
                     break
 
             # If there has been any change in membership, include them in the