Bug#1021402: reproducible: Please force merged-/usr for build2

[Luca Boccassi]

On Fri, 7 Oct 2022 at 16:21, Simon McVittie <smcv at debian.org> wrote:
>
> Package: jenkins.debian.org
> Severity: normal
> X-Debbugs-Cc: usrmerge at packages.debian.org, debian-qa at lists.debian.org
>
> The reproducible builds infrastructure tries to vary the merged-/usr
> status of the build system, like this:
>
> - base tarball: explicitly disable merged-/usr
> - build1: leave merged-/usr disabled
> - build2: pass "--extrapackages usrmerge" to pbuilder, to convert the
>   system to merged-/usr
>
> This has been very useful for detecting bugs of the same class as
> <https://bugs.debian.org/1015188>.
>
> However, now that new chroots are merged-/usr by default, I don't think
> this is working as intended. Disabling merged-/usr during base chroot
> creation now creates a flag file /etc/unsupported-skip-usrmerge-conversion
> representing "please don't merge /usr, contrary to the default", and
> installing the usrmerge package is not sufficient to undo the effect of
> that flag file.
>
> I believe the procedure to convert a non-merged-/usr QA chroot to
> merged-/usr is now something like this:
>
> 1. ensure the usrmerge package is installed
> 2. rm /etc/unsupported-skip-usrmerge-conversion
> 3. dpkg-reconfigure usrmerge
>
> Please do that for reproducible builds in build2, reinstating the
> previous setup where build1 is not merged-/usr but build2 is. I think
> implementing this on reproducible builds will require adding a pbuilder
> hook that does steps 2 and 3?

Wouldn't it be sufficient to create the build2 chroot as merged-usr
from the start?

Kind regards,
Luca Boccassi