Correct monky patching of django User.

sigdispatch.py

# -*- coding: utf-8 -*-

from django.db.models import signals

def model_class_prepared(sender, **kwargs):
    if sender._meta.app_label == 'auth' and sender._meta.module_name == 'user':
        print "Monky patching user..."
        email_field = sender._meta.get_field("email")
        email_field.max_length = 200
        email_field._unique = True

        last_name = sender._meta.get_field("last_name")
        last_name.max_length = 200

        first_name = sender._meta.get_field("first_name")
        first_name.max_length = 200

signals.class_prepared.connect(model_class_prepared)