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 ... -- 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
