Problems with bugzilla and FAS account

[Michael Schwendt]

As the fedoraproject aliases have trouble forwarding mail to GMX, I've
changed my FAS account to use my Google Mail address. I've confirmed
the change meanwhile.

In bugzilla, however, my account still uses my GMX address. And I cannot
change that. When I try to change it, I get:

    There is already an account with the login name mschwendt AT gmail.com.

That looks as if the FAS sync script created a separate account for me.
Right?

Are there special requirements for FAS users? Do I need to change email
addr in bugzilla _before_ changing it in FAS? Or what is necessary to
get this right?