Comment 46 for bug 875343

Installing from scratch Ubuntu 18.10, with a customised full disk encryption partitioning scheme.
After setting up separate encrypted volumes with new filesystems for these mountpoints:
   / /boot /home swap
I started
   ubiquity
and forgot -b so it completed fast but crashed at end (it is a known bug: on a FDE setup -b is needed, grub must be installed after configuring GRUB_ENABLE_CRYPTODISK=y in /etc/default/grub).
So, I restarted with the switch
   ubiquity -b
and met this "bug". Which isn't, at least in one, my, case. It's a "feature": finding an existing installation, ubiquity uses dpkg-repack to save the customisations and transport them to the new installation; this takes very long time, enough to find and read the preceding 45 posts...
In case of a new installation, kill ubiquity and restart recreating empty filesystems is quicker than waiting the repacking of the whole release.

OTOH, there seems to be also real bug described here: when /var is a mountpoint.

Rethinking, there are 2 bugs. One is in front of the keyboard. Those who want to keep the existing customised configuration should not reinstall, but should should perform a
   do-release-upgrade
Catering for those who reinstall but want to keep previous settings is a bug, I say.