From 77a076bd25fc355c49251bcf489c0511c0f0f0af Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 3 Feb 2015 13:35:17 +0000
Subject: [PATCH] Set combinations is | and not +

---
 synapse/handlers/federation.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index b9b2e25d1f..653ab0dbfa 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -114,9 +114,9 @@ class FederationHandler(BaseHandler):
 
         event_ids = set()
         if state:
-            event_ids += {e.event_id for e in state}
+            event_ids |= {e.event_id for e in state}
         if auth_chain:
-            event_ids += {e.event_id for e in auth_chain}
+            event_ids |= {e.event_id for e in auth_chain}
 
         seen_ids = (yield self.store.have_events(event_ids)).keys()