Error happened on user login

I use another plugin for user login called Nextend-facebook-connect, and when user login by using facebook there is a waring message show.

Here is the message:
Warning: Missing argument 2 for woocommerce_load_persistent_cart() in /home/urworks/webapps/mag_test/wp-content/plugins/woocommerce/woocommerce-core-functions.php on line 215

I try to make some hotfix and it do work, but I’m not sure if it is okay.

Ordinary code:

215 function woocommerce_load_persistent_cart( $user_login , $user) {
 216     global $woocommerce;
 217

Here is my code:

215 function woocommerce_load_persistent_cart( $user_login ) {
 216     global $woocommerce;
 217     $user = get_user_by('login', $user_login);

If there are any problem for this hotfix, please let me know. Thanks!

http://wordpress.org/extend/plugins/woocommerce/