Issue Summary

Mirrored cards are now included in Calendar views (TRELLO-930), however when creating an iCalendar sync from the calendar views, Mirrored cards aren't included in this iCalendar sync.

Steps to Reproduce

1. Create a card and set a due date
2. Mirror that card
3. Go to the calendar view for the board the Mirror card is on
4. Create an iCalendar link
5. Sync the iCalendar link in an external calendar

Expected Results

The Mirrored cards should be visible in the Calendar view, and in the iCalendar sync

Actual Results

The Mirrored card is visible in the board calendar, however, it's not included in the iCalendar sync

Workaround

None available