Course Calendar block and Upcoming events block should not list user override dates for activities located in a different course that the student is also enrolled in

To reproduce the problem:

1. Create two different courses A and B.
2. Enrol student X in both courses.
3. Add Calendar block and Upcoming events block to Course B.
4. In course A : Add 3 activities that support user overrides: Quiz, Lesson, Assignment.
5. In course A : Set user override dates for Student X (in the near future - for the Upcoming events block to pick them up):
   Quiz - set a different quiz closing date and / or opening date
   Lesson - set a different closing date
   Assignment - set a different due date
6. Log in as Student X, visit Course B.

Encountered behaviour: Although the date events come from Course A, and should only be displayed in Course A, student X will see these events also in the Course B Calendar block and Course B Upcoming events block.

Expected behaviour: Student X should only see his/her user overrides in the course blocks deployed in the course where the pertinent activities are located (Course A), not in ANY course they are enrolled in (e.g. Course B) where a Calendar block and/or Upcoming events block has/have been added by the teacher.