Code review comment for lp:~mhall119/django-openid-auth/fixes-642132

A more general approach, which also solves the small catch:

The username should always be renamed if it has changed, one exception for this is when the same username exists for another openid-provider. If there is already an user with that username (same provider) then the old_user should be renamed to the name without number (if available) else to the name + first_available_number.

If the same username is kept by another openid-provider, the user should keep its old username (if exists), if a new user is created, it should be username1 (username2 etc which first is available)

Therefore in the example above:
  OPENIDPROVIDER
    User Ben(https://login.launchpad.net/+id/AAAA) change name to Ben1
    User Cees(https://login.launchpad.net/+id/ABCD) change name to Ben
  OPENIDCONSUMER
    Ben (previous Cees | https://login.launchpad.net/+id/ABCD) logs in =>
       user 'Ben1' (https://login.launchpad.net/+id/AAAA) should be renamed to 'Ben2'
       user 'Cees' should be renamed to 'Ben1'
    Ben2 (https://login.launchpad.net/+id/AAAA) logs in with username 'Ben1'
       user 'Ben1' (previous Cees | https://login.launchpad.net/+id/ABCD) should be renamed to 'Ben3'
       user 'Ben2' should be renamed to 'Ben1'

All next logins for Ben3 (Cees/Ben (https://login.launchpad.net/+id/ABCD)) should check if 'Ben' is available. If not, keep the old username