Comment 46 for bug 1874272

I have verified the fix using ubuntu-release-upgrader from noble-propesed:

First, I upgraded a container without the fix:

nr@six:~$ lxc launch ubuntu:jammy j
nr@six:~$ lxc exec j bash
root@j:~# do-release-upgrade -d
Checking for a new Ubuntu release

= Welcome to Ubuntu 24.04 LTS 'Noble Numbat' =

The Ubuntu team is proud to announce Ubuntu 24.04 LTS 'Noble Numbat'.

To see what's new in this release, visit:
  https://wiki.ubuntu.com/NobleNumbat/ReleaseNotes

Ubuntu is a Linux distribution for your desktop or server, with a fast
and easy install, regular releases, a tight selection of excellent
applications installed by default, and almost any other software you
can imagine available through the network.

We hope you enjoy Ubuntu.

== Feedback and Helping ==

If you would like to help shape Ubuntu, take a look at the list of
ways you can participate at

  http://www.ubuntu.com/community/participate/

Your comments, bug reports, patches and suggestions will help ensure
that our next release is the best release of Ubuntu ever. If you feel
that you have found a bug please read:

  http://help.ubuntu.com/community/ReportingBugs

Then report bugs using apport in Ubuntu. For example:

  ubuntu-bug linux

will open a bug report in Launchpad regarding the linux package.

If you have a question, or if you think you may have found a bug but
aren't sure, first try asking on the #ubuntu or #ubuntu-bugs IRC
channels on Libera.Chat, on the Ubuntu Users mailing list, or on the
Ubuntu forums:

  http://help.ubuntu.com/community/InternetRelayChat
  http://lists.ubuntu.com/mailman/listinfo/ubuntu-users
  http://www.ubuntuforums.org/

== More Information ==

You can find out more about Ubuntu on our website, IRC channel and wiki.
If you're new to Ubuntu, please visit:

  http://www.ubuntu.com/

To sign up for future Ubuntu announcements, please subscribe to Ubuntu's
very low volume announcement list at:

  http://lists.ubuntu.com/mailman/listinfo/ubuntu-announce

Continue [yN] y
Get:1 Upgrade tool signature [833 B]
Get:2 Upgrade tool [1278 kB]
Fetched 1279 kB in 0s (0 B/s)
authenticate 'noble.tar.gz' against 'noble.tar.gz.gpg'
extracting 'noble.tar.gz'
[screen is terminating]
root@j:~# grep "checking for obsolete pkgs" /var/log/dist-upgrade/main.log
2024-08-12 19:48:42,704 DEBUG Start checking for obsolete pkgs
2024-08-12 19:48:51,918 DEBUG Finish checking for obsolete pkgs
root@j:~# grep "The following packages are marked for removal" /var/log/dist-upgrade/main.log
2024-08-12 19:48:51,974 DEBUG The following packages are marked for removal: libperl5.34 python3.10 libctf-nobfd0 libblockdev-part2 libblockdev-swap2 libpcre3 libunistring2 libaio1 libmpdec3 libbinutils python3-jeepney libpython3.10-minimal libblockdev-fs2 libpython3.10-stdlib binutils-x86-64-linux-gnu irqbalance libbpf0 libtss2-mu0 libldap-2.5-0 isc-dhcp-common libisc-export1105 libappstream4 libpython3.10 libblockdev-loop2 libblockdev2 libblockdev-part-err2 isc-dhcp-client libctf0 libnsl2 libblockdev-utils2 python3-jaraco.classes libprocps8 binutils-common libdns-export1110 libsframe1 pkexec python3-keyring libgprofng0 libcbor0.8 python3.10-minimal perl-modules-5.34 ubuntu-advantage-tools gcc-12-base libblockdev-crypto2 libicu70 libnetplan0 policykit-1 binutils python3-secretstorage

Then, in different container, I used the upgrader from noble-proposed:

nr@six:~$ lxc launch ubuntu:jammy j2
nr@six:~$ lxc exec j2 bash
root@j2:~# sed -i 's/Prompt=lts/Prompt=normal/g' /etc/update-manager/release-upgrades
root@j2:~# do-release-upgrade --proposed
Checking for a new Ubuntu release

= Welcome to Ubuntu 24.04 LTS 'Noble Numbat' =

The Ubuntu team is proud to announce Ubuntu 24.04 LTS 'Noble Numbat'.

To see what's new in this release, visit:
  https://wiki.ubuntu.com/NobleNumbat/ReleaseNotes

Ubuntu is a Linux distribution for your desktop or server, with a fast
and easy install, regular releases, a tight selection of excellent
applications installed by default, and almost any other software you
can imagine available through the network.

We hope you enjoy Ubuntu.

== Feedback and Helping ==

If you would like to help shape Ubuntu, take a look at the list of
ways you can participate at

  http://www.ubuntu.com/community/participate/

Your comments, bug reports, patches and suggestions will help ensure
that our next release is the best release of Ubuntu ever. If you feel
that you have found a bug please read:

  http://help.ubuntu.com/community/ReportingBugs

Then report bugs using apport in Ubuntu. For example:

  ubuntu-bug linux

will open a bug report in Launchpad regarding the linux package.

If you have a question, or if you think you may have found a bug but
aren't sure, first try asking on the #ubuntu or #ubuntu-bugs IRC
channels on Libera.Chat, on the Ubuntu Users mailing list, or on the
Ubuntu forums:

  http://help.ubuntu.com/community/InternetRelayChat
  http://lists.ubuntu.com/mailman/listinfo/ubuntu-users
  http://www.ubuntuforums.org/

== More Information ==

You can find out more about Ubuntu on our website, IRC channel and wiki.
If you're new to Ubuntu, please visit:

  http://www.ubuntu.com/

To sign up for future Ubuntu announcements, please subscribe to Ubuntu's
very low volume announcement list at:

  http://lists.ubuntu.com/mailman/listinfo/ubuntu-announce

Continue [yN] y
Get:1 Upgrade tool signature [833 B]
Get:2 Upgrade tool [1280 kB]
Fetched 1281 kB in 0s (0 B/s)
authenticate 'noble.tar.gz' against 'noble.tar.gz.gpg'
extracting 'noble.tar.gz'
[screen is terminating]
root@j2:~# grep "checking for obsolete pkgs" /var/log/dist-upgrade/main.log
2024-08-12 20:02:58,758 DEBUG Start checking for obsolete pkgs
2024-08-12 20:02:59,396 DEBUG Finish checking for obsolete pkgs
root@j2:~# grep "The following packages are marked for removal" /var/log/dist-upgrade/main.log
2024-08-12 20:02:59,468 DEBUG The following packages are marked for removal: libperl5.34 python3.10 libctf-nobfd0 libblockdev-part2 libblockdev-swap2 libpcre3 libunistring2 libaio1 libmpdec3 libbinutils python3-jeepney libpython3.10-minimal libblockdev-fs2 libpython3.10-stdlib binutils-x86-64-linux-gnu irqbalance libbpf0 libtss2-mu0 libldap-2.5-0 isc-dhcp-common libisc-export1105 libappstream4 libpython3.10 libblockdev-loop2 libblockdev2 libblockdev-part-err2 isc-dhcp-client libctf0 libnsl2 libblockdev-utils2 python3-jaraco.classes libprocps8 binutils-common libdns-export1110 libsframe1 pkexec python3-keyring libgprofng0 libcbor0.8 python3.10-minimal perl-modules-5.34 ubuntu-advantage-tools gcc-12-base libblockdev-crypto2 libicu70 libnetplan0 policykit-1 binutils python3-secretstorage

As can be seen from the above, the "searching for obsoletes" stage was significantly faster in the second upgrade, and the list of removals is the same.