channeld: accept SHUTDOWN before channel is locked.

Fixes: #1308
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

channeld/channel.c

@@ -1589,7 +1589,9 @@ static void peer_in(struct peer *peer, const u8 *msg)
 
 	/* Must get funding_locked before almost anything. */
 	if (!peer->funding_locked[REMOTE]) {
-		if (type != WIRE_FUNDING_LOCKED && type != WIRE_PONG) {
+		if (type != WIRE_FUNDING_LOCKED
+		    && type != WIRE_PONG
+		    && type != WIRE_SHUTDOWN) {
 			peer_failed(&peer->cs,
 				    peer->gossip_index,
 				    &peer->channel_id,

lightningd/channel_control.c

@@ -77,9 +77,9 @@ static void peer_got_shutdown(struct channel *channel, const u8 *msg)
 	}
 
 	/* If we weren't already shutting down, we are now */
-	if (channel->state == CHANNELD_NORMAL)
+	if (channel->state != CHANNELD_SHUTTING_DOWN)
 		channel_set_state(channel,
-				  CHANNELD_NORMAL, CHANNELD_SHUTTING_DOWN);
+				  channel->state, CHANNELD_SHUTTING_DOWN);
 
 	/* TODO(cdecker) Selectively save updated fields to DB */
 	wallet_channel_save(ld->wallet, channel);