make sure we only set lock_height if >0

libwallet/src/internal/selection.rs

@@ -286,9 +286,10 @@ where
 	let (mut parts, change_amounts_derivations) =
 		inputs_and_change(&coins, wallet, keychain_mask, amount, fee, change_outputs)?;
 
-	// This is more proof of concept than anything but here we set lock_height
-	// on tx being sent (based on current chain height via api).
-	parts.push(build::with_lock_height(lock_height));
+	// Build a "Plain" kernel unless lock_height>0 explicitly specified.
+	if lock_height > 0 {
+		parts.push(build::with_lock_height(lock_height));
+	}
 
 	Ok((parts, coins, change_amounts_derivations, fee))
 }