601         else:

   601         else:

   602             return None

   602             return None

   603     

   603     

   604         

   604         

   605     def create_inactive_user(self, email, send_invitation, **kwargs):

   605     def create_inactive_user(self, email, send_invitation, **kwargs):

   607             #prevent concurrent access 

   607             #prevent concurrent access 

   608             cursor = connection.cursor()

   608             cursor = connection.cursor()

   609             sql = "LOCK TABLE auth_user IN EXCLUSIVE MODE"

   609             sql = "LOCK TABLE auth_user IN EXCLUSIVE MODE"

   610             cursor.execute(sql)

   610             cursor.execute(sql)

   611         

   611