Overrides visible for all courses from the calendar

An override for an activity in course A is visible from the calendar for all other courses, even seen separately

The event is not only displayed for the desired course

Steps :

• login as teacher in "course 1"
• add an assignement with due and cut-off date (July 8th)
• add an user overrides for a student (July 9th)

• login as student (student must have at least 2 courses)
• go to Dashboard
• verify if activity is due to July 9th
• add filter based on "course 1"
• verify if activity is due to July 9th
• add filter based on "course 2"
• verify if activity IS NOT SHOWNED

Tested on sandbox, student can see this course 1 event in course 2 view from calendar.