debian-installer stuck due to existing logind.conf

[sebi]

I'm trying to install Ubuntu server 14.04 from a USB-Stick created with usb-creator-gtk.
I configured one boot partition and a raid partition for root and swap each. I chose to encrypt these two partitions.
After the installation of the base system I chose not to install any software, but to auto-install security updates. While this next step the progress is stopped and looking at TTY4 seams to give a reason.
A configuration file /etc/systemd/logind.conf is already existing and a dialog is shown on what to do. Since this is not interactive I don't see any possiblity to proceed with the installation.
I would really appreciate a hint how to work around this issue, so that I can install Ubuntu.

[sebi (sebi1)]

added a photo of the log output on virtual console visualizing the issue