Select All check box not getting checked when disabled rows present

I am using the version 4.1.0 of ui-grid. I have enabled the row selection header.

I have two rows in the grid. One row is disabled using isRowSelectable(). Now if i check select all, the enabled row gets selected and the disabled row is not selected. That's fine.

Now if i unselect that enabled row, select all checkbox too gets unselected. That too fine.

But now if i select that enabled row alone, select all checkbox is not checked. It has only two rows and in that one enabled row is checked, So here i expect select all check box to be checked.

http://plnkr.co/edit/A6r6sfzA3CJhZp4SulhQ?p=preview