When restoring a backed up course, attributes 'locked by dependencies' due to a setting on a previous screen are still locked after the user goes back to the previous screen and changes the original setting.

Steps to reproduce:

1. Back up a course with activities.
2. Click the 'restore' link next to a backup file.
3. Click 'Continue'.
4. Restore the course as a new course and click 'Continue'.
5. Uncheck 'Include activities and resources' checkbox and click 'Next'.
6. Notice the activities checkboxes are correctly replaced by 'locked by dependencies' icon and alt text.
7. Click 'Previous' or hit your browser's 'back' button, we've tested both.
8. Check 'Include activities and resources' checkbox and click 'Next'.
9. Notice the activities are still, now incorrectly, replaced by 'locked by dependencies' icon and alt text.