gw_buffer was not freed.

server/modules/protocol/mysql_common.c

@@ -805,6 +805,7 @@ mysql_send_custom_error (DCB *dcb, int packet_number, int in_affected_rows, cons
         // writing data in the Client buffer queue
         dcb->func.write(dcb, buf);
 
+        gwbuf_free(buf);
         return sizeof(mysql_packet_header) + mysql_payload_size;
 }