After deleting all layers inside a group contents remains in display as if the group had layers. The group ghost contents disappear after adding one empty layer but reappear if group is left empty again.

Reproducible: Always

Steps to Reproduce:
1. Create a group layer with 2 paint layers in it (It only works with more than one layer inside the group)
2. Paint something in both layers
3. Delete layers leaving the group empty
Actual Results:  
Deleted pixel data reappears in the group

Expected Results:  
group layer should display nothing if empty.