fix Use v2 reserve condition for spliced-from-v1 v2 channels as well

Author: optout21

lightning/src/ln/channel.rs

@@ -10591,7 +10591,7 @@ where
 		}
 		// We're not allowed to dip below the reserve once we've been above,
 		// check differently for originally v1 and v2 channels
-		if self.is_v2_established() {
+		if self.is_v2() {
 			let pre_channel_reserve_sats =
 				get_v2_channel_reserve_satoshis(pre_channel_value_sats, dust_limit_sats);
 			if pre_balance_msat >= (pre_channel_reserve_sats * 1000) {
@@ -11386,6 +11386,17 @@ where
 		// CHANNEL_ANNOUNCEMENT_PROPAGATION_DELAY confirmations.
 		self.context.historical_scids.drain(0..end)
 	}
+
+	/// Check is channel is currently v2:
+	/// - established as v2
+	/// - or past a splice (which implicitly makes the channel v2)
+	fn is_v2(&self) -> bool {
+		if self.funding.channel_transaction_parameters.splice_parent_funding_txid.is_some() {
+			true
+		} else {
+			self.is_v2_established()
+		}
+	}
 }
 
 /// A not-yet-funded outbound (from holder) channel using V1 channel establishment.