Comment 1 for bug 2041707

There isn't anything we can do in apt about this sadly. The implementation that would work correctly for this case (which uses pinning to implement phasing) breaks the solver in most cases.

Trying to switch candidates in the upgrader code is also not something I'd be interested in, it would likely again break systems.

Hence reassigning this to ubuntu-release-upgrader to do set the always-include-phased-updates option (don't remember full name, lookup phased update in apt discourse post) in apt_pkg.config object.

The pinning based implementation that would solve this particular issue is also available via a configuration option but it would break the solver as soon as lunar-updates had a newer version than mantic-updates for one binary and we try to install another binary of the same source package.

This means people upgrading releases get phased upgrades installed. Sadly it's an all or nothing right now, and no phased upgrades doesn't work in this particular case as it has the same behaviour as the bug.

The real solution involves writing a new solver that doesn't just remove packages due to unsatisfied dependencies, which is somewhat in progress (see https://salsa.debian.org/apt-team/solver3 for the concepts) and then we can be happy.