Fix crash on loging into the admin database

[PierreDucroquet]

The admin database is restricted, the global auth_user setting does not apply to it. Not doing so crashes pgbouncer when an unknown user logs in to the admin db.

fix #568

[petere]

I don't think this is the right solution for the original problem. As discussed there, the root cause there is really in the way users are managed internally in pgbouncer. Restricting how users can be used just papers over one particular symptom but doesn't fix anything. AFAICT, the crash only happens when you use "pgbouncer" as the auth_user, so there is an available workaround.

[sdigit]

I don't think this is the right solution for the original problem. As discussed there, the root cause there is really in the way users are managed internally in pgbouncer. Restricting how users can be used just papers over one particular symptom but doesn't fix anything. AFAICT, the crash only happens when you use "pgbouncer" as the auth_user, so there is an available workaround.

I get this crash when attempting to login to postgres when postgres is not configured in pgbouncer.ini; the username is not pgbouncer in my case. I just ran into it when connected to a database I wanted to drop, trying to switch to postgres.