remove unused variable

Author: arik-so

lightning/src/routing/network_graph.rs

@@ -1111,7 +1111,7 @@ impl NetworkGraph {
 		let mut channels = self.channels.write().unwrap();
 		let mut nodes = self.nodes.write().unwrap();
 		match channels.entry(short_channel_id) {
-			BtreeEntry::Occupied(mut entry) => {
+			BtreeEntry::Occupied(_) => {
 				// given that duplicate announcements are fine with a gossip sync scenario,
 				// perhaps we could just return `Ok(())` here
 				return Err(LightningError{err: "Already have knowledge of channel".to_owned(), action: ErrorAction::IgnoreDuplicateGossip});