CLONE - When a Safe Exam Browser requiring quiz is forced to have a password set, it can’t be saved when that is left empty.

Test Steps:

1. Login as an admin, edit the setting quizpasswordrequired (Site administration → Plugins → Activity modules → Quiz Safe Exam Browser access rule → Quiz password required) to be checked.
2. Login as a teacher, add an activity of type quiz to a course.
3. In the quiz, edit the settings for 'Require the use of Safe Exam Browser' to be 'Yes – Configure manually'.
4. In the quiz settings, omit a value for 'Require password' (under 'Extra restrictions on attempts').
5. Try to save the activity.
6. CONFIRM the user interface refuses to save and displays 'Using Safe Exam Browser requires to set a quiz password' next to the 'Require password' field.
7. Set a value for 'Require password' (under 'Extra restrictions on attempts').
8. Try to save the activity.
9. VERIFY it saves correctly.
10. Re-edit the quiz and edit the settings for 'Require the use of Safe Exam Browser' to be 'No'.
11. In the quiz settings, omit a value for 'Require password' (under 'Extra restrictions on attempts').
12. Try to save the activity.
13. VERIFY it saves correctly.