Changing user rights for one folder results in changed user rights for another folder

Sometimes when changing user rights for one folder in a course the user rights for another folder in that course are changed as well.

This can happen if a course suffers from OO-5575. The list of rights of the course nodes are aliases from a specific one, and the changes are shared across the nodes. The goal of the issue is to break the alias by copying the list if the settings are changed.