Group assignments can be undone after submission

[#1]

This case cannot be reproduced.

Description

Group assignments can be set as non-group assignments after students have submitted.

Expected Behavior

The group setting should be immediately locked after students have submitted.

Steps to Reproduce

Prerequisites: A course with at least 2 students

1. Create a group set and add the student to a group

2. Create a group assignment assigned to the group set

3. As a student, submit to the group assignment

4. Navigate to the assignment edit page, see that the option to modify the group assignment setting are able to be edited

5. Bonus round: Re-save the assignment and see the setting is now locked

Additional Info

DEMO-85