Fix keep-alive again (missing cleanup)

src/server.c

@@ -112,6 +112,7 @@ static void server_keepalive_cb(struct ev_loop *loop, ev_timer *w, int revents)
 		ev_tstamp remaining = con->keep_alive_data.max_idle - srv->keep_alive_queue_timeout - (now - con->keep_alive_data.timeout);
 		if (remaining > 0) {
 			g_queue_delete_link(q, l);
+			con->keep_alive_data.link = NULL;
 			ev_timer_set(&con->keep_alive_data.watcher, remaining, 0);
 			ev_timer_start(srv->loop, &con->keep_alive_data.watcher);
 		} else {