Bug#1052058: apt: refuses to downgrade itself to a version that works on the system
Control: severity -1 serious
As maintainer, I do consider this a blocker for testing migration.
On Sat, Sep 16, 2023 at 08:36:21PM +0200, Adam Borowski wrote:
> Package: apt
> Version: 2.7.5
> Severity: important
>
>
> Once again we have a package that some people consider broken. That's
> natural, disagreements happen. That apt insists on a bad scheme not
> supported by dpkg has been said about elsewhere. Normally, that would
> be solvable by a simple downgrade.
>
> Except, in this case, apt refuses to do this:
>
> # apt install apt=2.7.3 apt-utils=2.7.3
> Reading package lists... Done
> Building dependency tree... Done
> Reading state information... Done
> Suggested packages:
> apt-doc
> The following packages will be DOWNGRADED:
> apt apt-utils
> 0 upgraded, 0 newly installed, 2 downgraded, 0 to remove and 2 not upgraded.
> E: /bin resolved to a different inode than /usr/bin
> E: Unmerged usr is no longer supported, install usrmerge to continue.
> N: See https://www.debian.org/releases/bookworm/amd64/release-notes/ch-information.en.html#a-merged-usr-is-now-required for more details.
>
> As you can see, the action I requested specifically solves the problem,
> yet apt considers it no good. Thus, I'd need to take steps that are not
> obvious to a regular user, and for this specific package risky to break the
> system if done wrong.
>
> Thus, apt should consider an operation that touches apt itself to be
> another exception for the usrmerge demand.
Thank you for your bug report.
I have considered the situation and I believe that all downgrades
should be considered safe operations, so as long as all operations
are downgrades, they may go ahead.
On the flip side, this also shows we need to build mechanisms to
ensure repositories are not being used by apt versions that do
not support the features required by the repositories, so we
will be implementing a feature flag mechanism in Release files
to that effect.
Perhaps we should also have a Depends field in Release files
so that repositories can list minimum versions of essential
packages.
This would have addressed this issue in that you could downgrade
but would be unable to continue to use Debian repositories.
Perhaps more importantly, this allows us to roll out critical
fixes to stable-updates and enforce that users have upgraded
to those when upgrading to testing.
This will severely improve our ability to deal with upgrade
problems outside of hacking package dependencies or hoping
people read release notes.
--
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