Backup dependencies contain logic bugs.

Backup a course with many activities. On the first page of the backup process, uncheck "Include enrolled users".  Proceed to the second page of the backup process. Verify that all of the "user data" options are displayed as a red cross and cannot be turned on. Use the "Previous" button to return to the first page of the backup process. Check the "Include enrolled users" checkbox again. Verify that the "Include user role assignments" setting is enabled. Proceed to the second page of the backup process. Verify that all of the "User data" settings are enabled and checked. Complete the backup. No debugging messages should appear anywhere.  Restore the backup to a new course. On the first page of the restore process (the one with '3. Settings' in the 'breadcrumb'), uncheck "Include enrolled users".  Proceed to the second page of the restore process (the one with '4. Schema' in the 'breadcrumb'). Verify that none of the "User data" settings can be enabled. Use the "Previous" button to return to the first page of the restore process. Check the "Include enrolled users" checkbox again. Verify that the "Include user role assignments" setting is enabled. Proceed to the second page of the restore process. Verify that all of the "User data" settings are enabled and checked. Complete the restore. No debugging messages should appear anywhere.