Small bug in a recent update.

line 387
if ($next_zone['zone_id'] < 1 || $next_zone['zone_id'] === $order->delivery['zone_id']) {

fails to work because of ===. $next_zone['zone_id'] is not an int the way $order->delivery['zone_id'] is.
Casting fixes.

The symptom is the shipping estimator does not show UPSXML rates prior to login for users who restrict UPSXML by Zone.