f - Avoid unnecessary extra allocation

Author: ViktorTigerstrom

lightning/src/ln/channelmanager.rs

@@ -3099,7 +3099,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 			let channel_state = &mut *channel_state_lock;
 
 			let mut forward_htlcs = HashMap::new();
-			mem::swap(&mut forward_htlcs, &mut self.forward_htlcs.lock().unwrap().drain().collect());
+			mem::swap(&mut forward_htlcs, &mut self.forward_htlcs.lock().unwrap());
 
 			for (short_chan_id, mut pending_forwards) in forward_htlcs {
 				if short_chan_id != 0 {