channeld: don't send ANNOUNCEMENT_SIGNATURES if we've send shutdown.

Our closingd doesn't handle it:

lightningd(2968): 0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518 chan #1:
 Peer permanent failure in CLOSINGD_SIGEXCHANGE: lightning_closingd: sent ERROR Expected closing_signed:
 0103ff54517293892ec3f214f2343c54cbfbf24aa6ffb8d5585d3bc1b543eae0a272000067000001000146390e0c043c777226927eacd2186a03f064e4bdc30f891cb6e4990af49967d34b338755e99d728987e3d49227815e17f3ab40092434a59e33548e870071176d26d19a4e4d8f7715c13ac2d6bf3238608a1ccf9afd91f774d84d170d9edddebf7460c54d49bd6cd81410bc3eeeba2b7278b1b5f7e748d77d793f31086847d582

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

channeld/channel.c

@@ -473,6 +473,10 @@ static void handle_peer_funding_locked(struct peer *peer, const u8 *msg)
 	if (peer->funding_locked[REMOTE])
 		return;
 
+	/* Too late, we're shutting down! */
+	if (peer->shutdown_sent[LOCAL])
+		return;
+
 	peer->old_remote_per_commit = peer->remote_per_commit;
 	if (!fromwire_funding_locked(msg, &chanid,
 				     &peer->remote_per_commit))
@@ -1930,6 +1934,10 @@ static void handle_funding_locked(struct peer *peer, const u8 *msg)
 					     &peer->short_channel_ids[LOCAL]))
 		master_badmsg(WIRE_CHANNEL_FUNDING_LOCKED, msg);
 
+	/* Too late, we're shutting down! */
+	if (peer->shutdown_sent[LOCAL])
+		return;
+
 	per_commit_point(&peer->shaseed,
 			 &next_per_commit_point, peer->next_index[LOCAL]);
 
@@ -1954,6 +1962,10 @@ static void handle_funding_announce_depth(struct peer *peer)
 	if (peer->announce_depth_reached)
 		return;
 
+	/* Too late, we're shutting down! */
+	if (peer->shutdown_sent[LOCAL])
+		return;
+
 	peer->announce_depth_reached = true;
 	send_announcement_signatures(peer);
 
@@ -2531,9 +2543,12 @@ static void init_channel(struct peer *peer)
 	if (funding_signed)
 		enqueue_peer_msg(peer, take(funding_signed));
 
+	/* Don't send if we're shutting down */
+	if (!peer->shutdown_sent[LOCAL]) {
 		/* It's possible that we died previously before doing these. */
 		send_temporary_announcement(peer);
 		send_announcement_signatures(peer);
+	}
 
 	billboard_update(peer);
 	tal_free(msg);