Debian 8 express installation is broken due to the tentative of installing qemu-guest-agent. It happens because there no mirror is setup during the installation* and the package is not part of the DVD1 (used during the installation). *: https://bugzilla.redhat.com/show_bug.cgi?id=1336110
Pushed a fix (21c828ae8) and it will be available on 0.3.1 release.