fix merge problem. assign_default_role() ended up being defined twice as that code was added in both master and cms-master branches, but the merge didn't pick it up as a conflict

lms/djangoapps/django_comment_client/models.py

@@ -62,14 +62,3 @@ class Permission(models.Model):
 
     def __unicode__(self):
         return self.name
-
-
-@receiver(post_save, sender=CourseEnrollment)
-def assign_default_role(sender, instance, **kwargs):
-    if instance.user.is_staff:
-        role = Role.objects.get_or_create(course_id=instance.course_id, name="Moderator")[0]
-    else:
-        role = Role.objects.get_or_create(course_id=instance.course_id, name="Student")[0]
-
-    logging.info("assign_default_role: adding %s as %s" % (instance.user, role))
-    instance.user.roles.add(role)