Is there a way to delete the due date when copying an assignment? I know I can do this when copying a course, however, I have had issues where I would copy an individual assignment, but because the due date was earlier either A) all of my students would receive automatic zeros for their assignments being "late" even if I change the due date after copying, or 
The previous due date would fall in a "previous semester" that is closed and I wouldn't be able to make any changes at all.
