Bug#1056628: udhcpc: file loss during upgrade due to Multi-Arch: same interacting with /usr-merge

[Helmut Grohne <helmut@subdivi.de>]

Package: udhcpc
Version: 1:1.36.1-6~exp.1
Severity: normal
User: helmutg@debian.org
Usertags: dep17p7

Hi Chris,

thanks for sitting down with me and doing this /usr-move. We aimed to be
careful and upload to experimental. Now dumat doesn't like your upload.
I'm trying to figure out why and whether this is an analyzer bug or a
real problem, so please do not move busybox to unstable for the time
bing.

What follows is details that you may skip entirely, but figured I better
write them down for my future self. So dumat figured that udhcpc is
Multi-Arch: same in bookworm and /sbin/udhcpc is a shared file. Then the
experimental package contains /usr/sbin/udhcpc. In theory, this could
result in a loss scenario, because you can install udhcpc for two
architecture in bookworm, dpkg --unpack the experimental one for one
architecture and then dpkg --remove the other. While you can unpack
udhcpc for two architectures, configuring it does not work out, because
it depends on busybox, which happens to implied to be Multi-Arch: no and
apt would never consider a solution where you'd have to coinstall
udhcpc. Also udhcpc was changed to an Architecture: all package later
and that also makes the issue unreproducible. In theory, the detector
should have noticed that the experimental package is not coinstallable
with itself and therefore the alleged problem cannot be exercised.

I think the latter is an analyzer bug and should have prevented the
issue from being displayed. In the mean time, please avoid uploading
this to unstable. I'll either close this bug or upgrade it to rc once I
have a better understanding of what's going on.

Helmut