No option for specifying username format

[Kanishk Dewan]

When specifying the following setting to pick the username from email id:

OPENID_USE_EMAIL_FOR_USERNAME = True

I don't have an option to specify how the username should be formatted.
By default it just keeps all alphanumeric characters.

So for example if the email id of the user is:
    <email address hidden>

The username selected is:
    firstlastdomaincom

I want to be able to specify the format.

Currently I have to change line 157 in auth.py
From-
    suggestion = ''.join([x for x in email if x.isalnum()])
To-
    suggestion = email.split('@')[0]

So that I get only the username part.

For doing so I have to include the whole source code of django-openid-auth in my source code.