Removing a row when all are expanded, everything will collapse leaving the button as "-" (expanded)

[christoth305]

I have a grid with 2 levels with expandable options and delete rows for the first level grid.
After delete any row, the data is reloaded, its ok if everything is collapsed, the issue is : the button is showing "-" instead of "+"
Steps:

1. Expand all rows
   
2. Delete 1 row
   
3. The grid is reloaded and the button is "-"
   

Plunker: http://plnkr.co/edit/TJFaWv2KERcEZghz6scj?p=preview