From 8e254862f49e5183b0a0e9c4a41ae1f1c3477418 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Tue, 18 Aug 2015 11:11:33 +0100
Subject: [PATCH] Don't assume @cachedList function returns keys for everything

---
 synapse/util/caches/descriptors.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 83bfec2f0..362944bc5 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -293,7 +293,7 @@ class CacheListDescriptor(object):
                 # we can insert the new deferred into the cache.
                 for arg in missing:
                     observer = ret_d.observe()
-                    observer.addCallback(lambda r, arg: r[arg], arg)
+                    observer.addCallback(lambda r, arg: r.get(arg, None), arg)
 
                     observer = ObservableDeferred(observer)