From b1da3fa0a78ab7c6af8c274b6c2beafb7a5a751a Mon Sep 17 00:00:00 2001
From: "Paul \"LeoNerd\" Evans" <paul@matrix.org>
Date: Thu, 28 Aug 2014 16:19:16 +0100
Subject: [PATCH] Avoid AlreadyCalledError from EDU sending failures

---
 synapse/federation/replication.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/synapse/federation/replication.py b/synapse/federation/replication.py
index 38ae360bcd..7868575a2e 100644
--- a/synapse/federation/replication.py
+++ b/synapse/federation/replication.py
@@ -541,7 +541,8 @@ class _TransactionQueue(object):
         )
 
         def eb(failure):
-            deferred.errback(failure)
+            if not deferred.called:
+                deferred.errback(failure)
         self._attempt_new_transaction(destination).addErrback(eb)
 
         return deferred