Comment 26 for bug 1768379

I preformed and upgrade of an Ubuntu Desktop system from xenial w/ -proposed enabled to bionic (after hacking DistUpgradeController.py not to disable -proposed) so that python3-minimal from bionic-proposed would be used and the upgrade proceeded without error.

bdmurray@clean-xenial-amd64:~$ grep -C10 python3-minimal /var/log/dist-upgrade/apt-term.log
Selecting previously unselected package python3.6-minimal.
Preparing to unpack .../python3.6-minimal_3.6.5-3_amd64.deb ...
Unpacking python3.6-minimal (3.6.5-3) ...
Processing triggers for libglib2.0-0:amd64 (2.48.2-0ubuntu1) ...
Processing triggers for man-db (2.7.5-1) ...
Setting up libssl1.1:amd64 (1.1.0g-2ubuntu4.1) ...
locale: Cannot set LC_ALL to default locale: No such file or directory
Setting up libpython3.6-minimal:amd64 (3.6.5-3) ...
Setting up python3.6-minimal (3.6.5-3) ...
(Reading database ... 246397 files and directories currently installed.)
Preparing to unpack .../python3-minimal_3.6.5-3ubuntu1_amd64.deb ...
Unpacking python3-minimal (3.6.5-3ubuntu1) over (3.5.1-3) ...
Selecting previously unselected package libreadline7:amd64.
Preparing to unpack .../libreadline7_7.0-3_amd64.deb ...
Unpacking libreadline7:amd64 (7.0-3) ...
Selecting previously unselected package libpython3.6-stdlib:amd64.
Preparing to unpack .../libpython3.6-stdlib_3.6.5-3_amd64.deb ...
Unpacking libpython3.6-stdlib:amd64 (3.6.5-3) ...
Selecting previously unselected package python3.6.
Preparing to unpack .../python3.6_3.6.5-3_amd64.deb ...
Unpacking python3.6 (3.6.5-3) ...
Preparing to unpack .../libpython3-stdlib_3.6.5-3ubuntu1_amd64.deb ...