Stanford-Online/class2go — pull request #2127 by jrbl (2013-02-05 01:00:42+00:00)
Title: Deleting Exam removes associations from Videos

@jbau please
* Deleting an exam will first look up all the videos which have a
foreignkey to it, and sets all their .exam properties to None. Then it
goes ahead with the deletion.
(closes #2043)