Merge branch 'feature/arjun/new-discussions' of github.com:MITx/mitx into…

Merge branch 'feature/arjun/new-discussions' of github.com:MITx/mitx into feature/arjun/new-discussions

lms/djangoapps/django_comment_client/utils.py

@@ -301,8 +301,12 @@ def permalink(content):
 def extend_content(content):
     roles = {}
     if content.get('user_id'):
+        try:
             user = User.objects.get(pk=content['user_id'])
             roles = dict(('name', role.name.lower()) for role in user.roles.filter(course_id=content['course_id']))
+        except user.DoesNotExist:
+            logging.error('User ID {0} in comment content {1} but not in our DB.'.format(content.get('user_id'), content.get('id')))
+        
     content_info = {
         'displayed_title': content.get('highlighted_title') or content.get('title', ''),
         'displayed_body': content.get('highlighted_body') or content.get('body', ''),