Errors must not be cached

For instance, if bob is returned an error because he does not have
the required grants, then if the error were cached, alice would
receive bob's error reply even if she has the required grants.

server/modules/filter/cache/cachefiltersession.cc

@@ -404,9 +404,8 @@ int CacheFilterSession::handle_expecting_response()
         switch ((int)MYSQL_GET_COMMAND(header))
         {
         case MYSQL_REPLY_OK:
-        case MYSQL_REPLY_ERR:
             store_result();
-
+        case MYSQL_REPLY_ERR:
             rv = send_upstream();
             m_state = CACHE_IGNORING_RESPONSE;
             break;