ensure python is marked for removal when upgrading from 18.04 to 20.04

Hello Brian, or anyone else affected,

Accepted ubuntu-release-upgrader into focal-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/ubuntu-release-upgrader/1:20.04.33 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-focal to verification-done-focal. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-focal. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

I tested an upgrade from Bionic to Focal with 'do-release-upgrade -p' using the apt-clone file mentioned in the bug description and an upgrade was successfully calculated.

ubuntu@grown-crow:~$ head /var/log/dist-upgrade/main.log
2021-05-17 21:02:59,243 INFO Using config files '['./DistUpgrade.cfg.bionic', '/etc/update-manager/release-upgrades.d/ubuntu-advantage-upgrades.cfg']'
2021-05-17 21:02:59,244 INFO uname information: 'Linux grown-crow 5.11.0-17-generic #18-Ubuntu SMP Thu May 6 20:10:11 UTC 2021 x86_64'
2021-05-17 21:02:59,495 INFO apt version: '1.6.13'
2021-05-17 21:02:59,495 INFO python version: '3.6.9 (default, Jan 26 2021, 15:33:00)
[GCC 8.4.0]'
2021-05-17 21:02:59,498 INFO release-upgrader version '20.04.33' started
2021-05-17 21:02:59,502 INFO locale: 'en_US' 'UTF-8'
2021-05-17 21:02:59,566 WARNING estimate_kernel_initrd_size_in_boot() returned '0' for kernel?
2021-05-17 21:02:59,566 WARNING estimate_kernel_initrd_size_in_boot() returned '0' for initrd?
2021-05-17 21:02:59,579 DEBUG Using 'DistUpgradeViewText' view
ubuntu@grown-crow:~$ grep "Do you want to start" /var/log/dist-upgrade/screenlog.0
Do you want to start the upgrade?

Additionally, the 7 duplicates of the is bug were able to upgrade using the version of the release upgrader from -proposed.

This bug was fixed in the package ubuntu-release-upgrader - 1:20.04.33

---------------
ubuntu-release-upgrader (1:20.04.33) focal; urgency=medium

  * DistUpgrade/DistUpgradeController.py: restore sources.list where possible
    if a KeyboardInterrupt event is received and redirect the output of
    gnome-session-inhibit to devnull so a message regarding Ctrl-C is not
    displayed. (LP: #1898026)
  * DistUpgrade/DistUpgradeQuirks.py: Restore code which ensured the python
    package was maked for removal. (LP: #1928397)
  * Update mirrors and translations.

 -- Brian Murray <email address hidden> Thu, 13 May 2021 16:38:41 -0700

The verification of the Stable Release Update for ubuntu-release-upgrader has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.