Calendar should not iterate through all categories

Before the patch Checkout the last weekly release before the patch has been integrated. For master: git checkout b63a3b04b154990497bd58255b4ed579d37b432a For 3.4: git checkout b63a3b04b154990497bd58255b4ed579d37b432a Enable performance information in the footer. Note: If using MDK, run mdk run mindev Create three course categories, and one course in each category Add the blocks Upcoming Events and Calendar to the dashboard if not already there. View the dashboard and take note of the number of DB reads and the writes to the core/coursecatrecords cache. Testing with the patch Checkout the latest integration branch. For master: git checkout master For 3.4: git checkout MOODLE_34_STABLE Purge caches View the dashboard with the patch and notice that both numbers decreased. View the dashboard again and see that the course categories for the calendar are now fetched from the core/calendar_categories cache. Create a course category event for each of the categories Create a new user and login as that user in a different browser Confirm that you don't see any of the course category events Enrol that user in the course in the first category As the second user, refresh the calendar Confirm that you now see the events for the first category Confirm that you don't see any of the course category events for the second or third categories As admin, open Site admin -> courses -> Manage courses and categories Find the second category, click on its cog icon, and choose "Assign roles" Assign the Manager role to your other user As the second user, refresh the calendar Confirm that you see the events for the first category Confirm that you see the events for the second category Confirm that you DO NOT see the events for the third category