The default group icon should not be displayed when there is no group picture

Setup

1. Create a course. Set its group mode to "Visible groups"
2. Enrol a student
3. Create the following groups in the course

   Group	Has picture?	Hide picture
   Group A	Yes	No
   Group B	Yes	Yes
   Group C	No	No

4. Add the student to all of the groups
5. Create a forum in the course

Discussion views

1. Login as the student
2. In the forum, create a discussion for each group.
3. Open any discussion.
4. Choose each view mode (e.g. Display replies in nested form, etc.)
5. Confirm that for all of the view modes, you only see the group picture for Group A.

Experimental nested view

1. Open the student's user menu and click "Preferences"
2. Click "Forum preferences"
3. Set "Use experimental nested discussion view" to "Yes"
4. Go back to any of the discussions.
5. Set the view mode to "Display replies in experimental nested form"
6. Confirm that for this view mode, you only see the group picture for Group A.