Update core (wiki cache fix).

Signed-off-by: Florent Bruneau <florent.bruneau@polytechnique.org>

diff --git a/core b/core
index ada4c57..6cc34b5 160000 (submodule)
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit ada4c57e583132ebdd44c3e67a50118bf8c68b92
+Subproject commit 6cc34b5041e235805e37756b146b86a62f104e2a