Steps to reproduce:

1. In one browser, log in as teacher.
2. Create a new quiz.
3. Add some questions.
4. Leave that browser open.
5. In another browser, log in as student.
6. Start an attempt at the quiz.
7. Back in the teacher's browser, try to repaginate the quiz, or delete a question.

Expected result: You should get an error since you cannot edit a quiz that has been attempted.

Actual result: The edit work!

Once you have reloaded the edit page, the restrictions are enforced.

The problem is that the Ajax scripts repaginate.php and edit_rest.php do not check the 'no attempts' condition.