gossipd: set sent flag when sending reply_short_channel_ids_end

Otherwise, if we don't announce the last node, we'll not flush this
out; it will be delayed until the next time we send gossip!

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

CHANGELOG.md

@@ -35,6 +35,7 @@ changes.
 - JSON RPC: `ping` now works even after one peer fails to respond.
 - JSON RPC: `getroute` `fuzzpercent` and `pay` `maxfeepercent` can now be > 100.
 - Protocol: fix occasional deadlock when both peers flood with gossip.
+- Protocol: fix occasional long delay on sending `reply_short_channel_ids_end`.
 
 ### Security
 

gossipd/gossipd.c

@@ -865,6 +865,7 @@ static bool create_next_scid_reply(struct peer *peer)
 							     &rstate->chain_hash,
 							     true);
 		queue_peer_msg(peer, take(end));
+		sent = true;
 		peer->scid_queries = tal_free(peer->scid_queries);
 		peer->scid_query_idx = 0;
 		peer->scid_query_nodes = tal_free(peer->scid_query_nodes);