Hierarchecal Select widget doesn't working when be putted inside Field Group

I tried to put the "Term reference" field with "Hierarchical Select" widget inside a "Field Groups", but unfortunately the hierarchy widget didn't work properly( when i selected a parent term, the widget didn't render a children terms selectbox, still stay same original selectbox). However, when i try to move this "Term reference" field out of "Field Group" then it back to work normally.
I investigated this module and founded that the hierarchicalSelectUpdate() jQuery function in hierarchical_select.js file has detected wrong parent selectbox's css selector id, so jQuery can't replace new selectbox html output for the old selectbox after we select on the parent term. When we put the "Term reference" field with "Hierarchical Select" widget inside a "Field Groups", then the "Field Group" will change the html wrapper of "Hierarchical Select", that caused the wrong detection of render function upper.
And, here's my simple patch for that issue.