Ability to add multiple option sets to a product

I was having trouble getting multiple values working with the option set reference field.

I fixed this (for myself) by modifying the function commerce_option_get_sets().

I modified the line:

  $sets = entity_load('commerce_option_set', isset($set_id) ? array($set_id) : FALSE);

to reset the entity, like so:

  $sets = entity_load('commerce_option_set', isset($set_id) ? array($set_id) : FALSE, array(), TRUE);

I have no idea if this is the right way, i was just totally stoked it worked.