ui-select2 set dirty flag after initialization when simple_tags mode is on

Hi guys!

In my project I use simple_tags option. But after the form containing select2 control is loaded, $pristine flag of select2 control and parent form is set to false and $dirty flag is set to true, which seems to be not correct. Here is plnkr for the issue: http://plnkr.co/edit/TjUscmd0vrMzEqOBURTe?p=preview. I found the way to fix it but I would like someone to review my changes and maybe give me advice how to do it better.

Thanks