Installation of Ubuntu Wily, Problem with debconf

[André Lehmann]

Hello,

I'm using FAI 5.0 and try to install Ubuntu 15.10 (wily).

I've created a basefile with mk-basefile (copied the part from trusty), 
the installation finished as expected with a running system.

But,

there's no keyboard configuration, the problem is debconf:

debconf: DbDriver "_ENV_stack": unable to save changes to: 
keyboard-configuration/toggle 
keyboard-configuration/store_defaults_in_debconf_db

Thats my debconf file:

keyboard-configuration  keyboard-configuration/xkb-keymap       select  de

(only one line for testing)

With dpkg-reconfigure keyboard-configuration on the finished system it's 
working as expected.

For Debian wheezy, jessie and ubuntu 14.10 the configuration run's as 
expected,too.

Any hints or help?

Regards,
André Lehmann