Fix validation funs return format bug
diff --git a/src/ddoc_cache_opener.erl b/src/ddoc_cache_opener.erl
index 4f8eb65..b2bf930 100644
--- a/src/ddoc_cache_opener.erl
+++ b/src/ddoc_cache_opener.erl
@@ -166,7 +166,7 @@
         end
     end, DDocs),
     ok = ets_lru:insert(ddoc_cache_lru, {DbName, validation_funs}, Funs),
-    exit({open_ok, Key, Funs});
+    exit({open_ok, Key, {ok, Funs}});
 open_ddoc({DbName, DDocId}=Key) ->
     try fabric:open_doc(DbName, DDocId, []) of
         {ok, Doc} ->