Recommendation: Edit profile with "autogenerate username" function

[Geddo]

Scenario:

1. User registers new account without username -> autogenerate username kicks and sets username to the email address
2. User goes to his profile (where username is not selected in fe-manager plugin settings) and updates his e-mail adress

What's happening: The email address is getting updated, but username not and as the user doesnt see the field he has no chance to login anymore, except he trys his old email address