Assigning roles to course category level seems broken

To reproduce...

1. Change the teacher role so that it can be assigned at the Course Category level

2. Create a new Category and create a couple of courses within it

3. Assign a user the role Teacher at the Course Category (they have no other assignments)

4. Log in as that teacher.

5. Attempt to enter one of the courses. Error: "You cannot enrol yourself in this course"