f! prevent downgrade

Author: wpaulino

lightning/src/chain/package.rs

@@ -287,7 +287,7 @@ impl_writeable_tlv_based!(HolderHTLCOutput, {
 	(0, amount_msat, required),
 	(2, cltv_expiry, required),
 	(4, preimage, option),
-	(6, opt_anchors, (default_value, None))
+	(6, opt_anchors, option)
 });
 
 /// A struct to describe the channel output on the funding transaction.