I also performed an upgrade of an Ubuntu 16.04 lxc container to artful w/ -proposed enabled without issue.
ubuntu@artful-upgrade:~$ grep -C10 python3-minimal /var/log/dist-upgrade/apt-term.log Unpacking python3-cryptography (1.9-1) over (1.2.3-1ubuntu0.1) ... Processing triggers for systemd (234-2ubuntu12.4) ... Processing triggers for ureadahead (0.100.0-19) ... Processing triggers for libc-bin (2.26-0ubuntu2.1) ... Setting up libssl1.0.0:amd64 (1.0.2g-1ubuntu13.6) ... Setting up libpython3.6-minimal:amd64 (3.6.3-1ubuntu1) ... Setting up libexpat1:amd64 (2.2.3-1) ... Setting up python3.6-minimal (3.6.3-1ubuntu1) ... Processing triggers for libc-bin (2.26-0ubuntu2.1) ... (Reading database ... 26272 files and directories currently installed.) Preparing to unpack .../python3-minimal_3.6.3-0ubuntu3_amd64.deb ... Unpacking python3-minimal (3.6.3-0ubuntu3) over (3.5.1-3) ... Setting up python3-minimal (3.6.3-0ubuntu3) ... (Reading database ... 26272 files and directories currently installed.) Preparing to unpack .../python3_3.6.3-0ubuntu3_amd64.deb ... running python pre-rtupdate hooks for python3.6... Unpacking python3 (3.6.3-0ubuntu3) over (3.5.1-3) ... Preparing to unpack .../install-info_6.4.90.dfsg.1-1build1_amd64.deb ... Unpacking install-info (6.4.90.dfsg.1-1build1) over (6.1.0.dfsg.1-5) ... Setting up install-info (6.4.90.dfsg.1-1build1) ... (Reading database ... 26272 files and directories currently installed.) Preparing to unpack .../readline-common_7.0-0ubuntu2_all.deb ... Unpacking readline-common (7.0-0ubuntu2) over (6.3-8ubuntu2) ... -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to python3-defaults in Ubuntu. https://bugs.launchpad.net/bugs/1768379 Title: python3-minimal should predepend on versioned version of python3-minimal Status in python3-defaults package in Ubuntu: Triaged Status in ubuntu-release-upgrader package in Ubuntu: Invalid Status in python3-defaults source package in Artful: Fix Committed Status in ubuntu-release-upgrader source package in Artful: Invalid Status in python3-defaults source package in Bionic: Fix Committed Status in ubuntu-release-upgrader source package in Bionic: Invalid Status in python3-defaults package in Debian: Fix Released Bug description: [Impact] Release upgrades from Ubuntu 16.04 LTS to either Ubuntu 17.10 or Ubuntu 18.04 LTS can fail if python3-minimial is unpacked before python3.x-minimal so a system won't have a usable python3 symlink. Then upgrades will fail because py3clean, used in prerm scripts of python3 packages, will fail with "not found". [Test Case] 1) on a Ubuntu 16.04 LTS system with python3-apt installed download debs for Ubuntu 17.10 or 18.04 LTS of python3-minimal and python3-apt 2) dpkg --unpack python3-minimal... 3) dpkg --unpack python3-apt... Observe the following Traceback: Preparing to unpack .../python3-apt_1.4.0_beta3build2_amd64.deb ... /var/lib/dpkg/info/python3-apt.prerm: 6: /var/lib/dpkg/info/python3-apt.prerm: py3clean: not found dpkg: warning: subprocess old pre-removal script returned error exit status 127 dpkg: trying script from the new package instead ... /var/lib/dpkg/tmp.ci/prerm: 6: /var/lib/dpkg/tmp.ci/prerm: py3clean: not found dpkg: error processing archive /home/jak/Downloads/python3-apt_1.4.0_beta3build2_amd64.deb (--unpack): subprocess new pre-removal script returned error exit status 127 /var/lib/dpkg/info/python3-apt.postinst: 6: /var/lib/dpkg/info/python3-apt.postinst: py3compile: not found dpkg: error while cleaning up: subprocess installed post-installation script returned error exit status 127 With the deb python3-minimal from -proposed you won't be able to unpack python3-minimal without first installing python3.6-minimal. While that may qualify as verification it'd still be good to test unpacking python3-apt. To do that you'll need to install python3.6-minimal from the target release by editing you /etc/apt/sources.list to the new release, running 'apt-get update', and then 'apt-get install python3.6-minimal'. After that's all done you can try steps 2 and 3 from the test case again and you should not receive a Traceback. [Regression Potential] Its possible this could cause or reveal different upgrade failures so some extensive (desktop, cloud, server) upgrade testing should be done. [A Portion of the Original Description (it was a huge blob of failure)] do-release-upgrade -d on my 16.04 LTS unity laptop lead to an install failure: To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/python3-defaults/+bug/1768379/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
