Preserve funding_transaction for the later lifecycle of the channel, simple solution

Author: optout21

lightning/src/ln/channel.rs

@@ -5486,7 +5486,8 @@ impl<SP: Deref> Channel<SP> where
 				(matches!(self.context.channel_state, ChannelState::AwaitingChannelReady(flags) if !flags.is_set(AwaitingChannelReadyFlags::WAITING_FOR_BATCH)) ||
 				matches!(self.context.channel_state, ChannelState::ChannelReady(_)))
 			{
-				self.context.funding_transaction.take()
+				// Take the funding transaction, do not clear the field
+				self.context.funding_transaction.clone()
 			} else { None };
 		// That said, if the funding transaction is already confirmed (ie we're active with a
 		// minimum_depth over 0) don't bother re-broadcasting the confirmed funding tx.
@@ -7893,6 +7894,7 @@ impl<SP: Deref> OutboundV1Channel<SP> where SP::Target: SignerProvider {
 			self.context.minimum_depth = Some(COINBASE_MATURITY);
 		}
 
+		debug_assert!(self.context.funding_transaction.is_none());
 		self.context.funding_transaction = Some(funding_transaction);
 		self.context.is_batch_funding = Some(()).filter(|_| is_batch_funding);
 

lightning/src/ln/payment_tests.rs

@@ -891,7 +891,7 @@ fn do_test_completed_payment_not_retryable_on_reload(use_dust: bool) {
 	nodes[0].node.timer_tick_occurred();
 	assert!(nodes[0].node.list_channels().is_empty());
 	assert!(nodes[0].node.has_pending_payments());
-	assert_eq!(nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0).len(), 1);
+	assert_eq!(nodes[0].tx_broadcaster.txn_broadcasted.lock().unwrap().split_off(0).len(), 4);
 	check_added_monitors!(nodes[0], 1);
 
 	nodes[0].node.peer_connected(nodes[1].node.get_our_node_id(), &msgs::Init {