if you're able to reproduce this, can you please put a 'set -x' on the second line of /usr/lib/ubiquity/apt-setup/apt-setup and /usr/lib/ubiquity/apt-setup/apt-setup-verify, then attempt to install again. When it crashes, attach /var/log/syslog to this bug report.
Ara,
if you're able to reproduce this, can you please put a 'set -x' on the second line of /usr/lib/ ubiquity/ apt-setup/ apt-setup and /usr/lib/ ubiquity/ apt-setup/ apt-setup- verify, then attempt to install again. When it crashes, attach /var/log/syslog to this bug report.
Thanks!