Consider channels with one direction useless for routing

This is actually only useful when we just restarted and received
an outdated channel update, which we keep for
STALE_CHANNEL_UPDATE_AGE_LIMIT_SECS to give
it a chance to send a channel update. During that time, we
still should not be used it for routing.

Author: naumenkogs

lightning/src/routing/router.rs

@@ -1274,7 +1274,9 @@ where L::Target: Logger {
 					for chan_id in $node.channels.iter() {
 						let chan = network_channels.get(chan_id).unwrap();
 						if !chan.features.requires_unknown_bits() {
-							if let Some((directed_channel, source)) = chan.as_directed_to(&$node_id) {
+							// We consider channels with only one direction filled useless,
+							// so we should check that both directions are present.
+							if chan.as_directed_from(&$node_id).is_some() && let Some((directed_channel, source)) = chan.as_directed_to(&$node_id) {
 								if first_hops.is_none() || *source != our_node_id {
 									if directed_channel.direction().enabled {
 										let candidate = CandidateRouteHop::PublicHop {