Kerberos problems with /dev/null as dovecot home

Hi,

this is for documentation if someone else has the same problem. After migration from Dovecot 1 to 2.2. it was no longer able use Kerberos (Heimdal). I found out that dovecot tries to read ~/.krb5/config in the home of the dovecot user. This file doesn't need to exist, but if the home is set to /dev/null, it will not work.

Maybe it would be nice to have an error message for this case.

Regards, Roland