Expected Behavior

No exception is raised.

Current Behavior

An exception is raised:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'NULL'

Possible Solution

Removed "NULL" from __all__ of __init__.py

Steps to Reproduce

1. from MySQLdb import *

Context (Environment)

It seems that "NULL" symbol is removed from MySQLdb/_mysql.c in 819688b
Also this issue occurs when google AppEngine deploys a local service for testing. rdbms_mysqldb.py

Possible Fix

#369