For a lower privilege user (like a teacher), a restore with questions in the system bank should be restored to the course question bank (and a warning as such is given to the user during the restore), but the files are actually placed in the system category. Files associated with the question are placed in the correct course category, resulting in a broken question.

We need to verify that a restore works correctly from the banks:
System
Course
Course Categories
Quiz

It also may be more generic permissions issue - i.e. if you get into a situation where a restorer doesn't have permissions to a particular question bank.

Steps to reproduce:

1. Make sure the system bank is empty
2. As a teacher, restore the attached file (Images-Test.mbz)
3. If you go to edit the quiz, you will notice that the question "System" is not editable by you
4. If you preview the quiz, you will notice that the question "System" has a broken image