Not a functional change. But while trying to figure out why gotd
was crashing in libevent, this stood out as a potential suspect
of libevent misuse.

-----------------------------------------------
 avoid calling event_del() for unrelated events in connect_session() 
 
 Rather, we can treat fd == -1 as a flag which tells gotd_request() to
 stop re-adding the event for this client. This seems cleaner.
 
diff 90270f794c7f4e1ce2b58c8b5bfdc190df4799b6 a993d087b9f1bd1801784b5b8ab7f84cec9d5664
commit - 90270f794c7f4e1ce2b58c8b5bfdc190df4799b6
commit + a993d087b9f1bd1801784b5b8ab7f84cec9d5664
blob - 00d1d81a42f9598ad0cba57a03f07fb868556714
blob + 2d3fb7e54d9404bb25410b6225921529fff39e24
--- gotd/gotd.c
+++ gotd/gotd.c
@@ -579,6 +579,10 @@ gotd_request(int fd, short events, void *arg)
 	struct imsg imsg;
 	ssize_t n;
 
+	/* Ignore events from clients which already have a session running. */
+	if (client->fd == -1)
+		return;
+
 	if (events & EV_WRITE) {
 		while (ibuf->w.queued) {
 			n = msgbuf_write(&ibuf->w);
@@ -1197,10 +1201,11 @@ connect_session(struct gotd_client *client)
 	/*
 	 * We are no longer interested in messages from this client.
 	 * Further client requests will be handled by the session process.
+	 * Clear outgoing message queues and set client->fd to -1 which will
+	 * cause gotd_request to ignore future messages from this client.
 	 */
 	msgbuf_clear(&client->iev.ibuf.w);
 	imsg_clear(&client->iev.ibuf);
-	event_del(&client->iev.ev);
 	client->fd = -1; /* will be closed via copy in client->iev.ibuf.fd */
 
 	return NULL;