Remove invalid splice debug assertion in funding_tx_constructed

We incorrectly assumed that both commitments must be at the same height,
but this is certainly possible whenever updates are proposed in both
directions at the same time.

Author: wpaulino

lightning/src/ln/channel.rs

@@ -6191,20 +6191,15 @@ where
 
 	#[rustfmt::skip]
 	fn funding_tx_constructed<L: Deref>(
-		&mut self, funding: &mut FundingScope, funding_outpoint: OutPoint, is_splice: bool,
+		&mut self, funding: &mut FundingScope, funding_outpoint: OutPoint,
 		holder_commitment_transaction_number: u64, logger: &L,
 	) -> Result<msgs::CommitmentSigned, AbortReason>
 	where
 		L::Target: Logger
 	{
 		funding.channel_transaction_parameters.funding_outpoint = Some(funding_outpoint);
 
-		if is_splice {
-			debug_assert_eq!(
-				holder_commitment_transaction_number,
-				self.counterparty_next_commitment_transaction_number,
-			);
-		} else {
+		if !is_splice {
 			self.assert_no_commitment_advancement(holder_commitment_transaction_number, "initial commitment_signed");
 			self.channel_state = ChannelState::FundingNegotiated(FundingNegotiatedFlags::new());
 		}