lightningd: move "tell gossipd peer is no longer important" to drop_to_chain.

Reported-by: @ZmnSCPxj
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/channel.c

@@ -324,7 +324,6 @@ void channel_fail_permanent(struct channel *channel, const char *fmt, ...)
 	va_list ap;
 	char *why;
 	struct channel_id cid;
-	u8 *msg;
 
 	va_start(ap, fmt);
 	why = tal_vfmt(channel, fmt, ap);
@@ -349,10 +348,6 @@ void channel_fail_permanent(struct channel *channel, const char *fmt, ...)
 		channel->error = towire_errorfmt(channel, &cid, "%s", why);
 	}
 
-	/* Tell gossipd we no longer need to keep connection to this peer */
-	msg = towire_gossipctl_peer_important(NULL, &channel->peer->id, false);
-	subd_send_msg(ld->gossip, take(msg));
-
 	channel_set_owner(channel, NULL);
 	/* Drop non-cooperatively (unilateral) to chain. */
 	drop_to_chain(ld, channel, false);

lightningd/closing_control.c

@@ -96,10 +96,6 @@ static void peer_closing_complete(struct channel *channel, const u8 *msg)
 	if (channel->state == CLOSINGD_COMPLETE)
 		return;
 
-	/* Tell gossipd we no longer need to keep connection to this peer */
-	msg = towire_gossipctl_peer_important(NULL, &channel->peer->id, false);
-	subd_send_msg(channel->peer->ld->gossip, take(msg));
-
 	/* Channel gets dropped to chain cooperatively. */
 	drop_to_chain(channel->peer->ld, channel, true);
 	channel_set_state(channel, CLOSINGD_SIGEXCHANGE, CLOSINGD_COMPLETE);

lightningd/peer_control.c

@@ -332,6 +332,12 @@ register_close_command(struct lightningd *ld,
 void drop_to_chain(struct lightningd *ld, struct channel *channel,
 		   bool cooperative)
 {
+	u8 *msg;
+
+	/* Tell gossipd we no longer need to keep connection to this peer */
+	msg = towire_gossipctl_peer_important(NULL, &channel->peer->id, false);
+	subd_send_msg(ld->gossip, take(msg));
+
 	sign_last_tx(channel);
 
 	/* Keep broadcasting until we say stop (can fail due to dup,