Sorting is broken when grid is expanded. App is stuck!

Hi all,

We have been using ui-grid (http://ui-grid.info/docs/#/tutorial/216_expandable_grid) in our project and currently facing with the following issue. I understand that expandable feature is still in alpha release.

Issue: Sorting is broken when grid is expanded and the grid becomes non-responsible.

Here's the plunker for reference: http://plnkr.co/edit/JvCwjInAFlzKnhjs51FR?p=preview

Steps to reproduce:

1. As soon as the grid is loaded, expand all elements by clicking on "Expand All" button or "+" icon.
2. Start sorting by "Dateofservice" column (2nd column).
3. Grid/app is frozen with the exception Uncaught Error: [$rootScope:infdig] 10 $digest() iterations reached. Aborting!

Notes:

1. When the grid is not expanded, sorting by all columns (including second column) is working without any issues.
2. After all nested grids are expanded, if I start sorting by any other column except the 2nd column and sort by 2nd column next, no issues. Everything works fine.
3. If I sort by 2nd column by expanding only one or two first nested grids, leaving all other grids in collapsed mode, sorting works without any problem.
4. This could be a bug or data issue. To be consistent with the expandable tutorial we are using complex.json data structure and have added couple extra data.

Can you please take a look into this issue and let me know your thoughts and comments?