Order status fail to sync with alipay(or paypal)

[yanggen]

my website use opencart framework,and i feel thankful for opencart.
The version of opencart I used is 1.5.5.1.
The problem is that,when I intergrated with alipay(something like paypal),I found that the order status can't sync.
Finally,I found that maybe ,in catalog/model/order.php ,function confirm($order_id, $order_status_id, $comment = '', $notify = false), if ($order_info &&!$order_info['order_status_id']){.....}, '!$order_info['order_status_id']' should be replace with'$order_info['order_status_id']' .
When I make the little change,everything work well now.So I suppose that it maybe a bug of opencart. Am I right?