Packages in PPA are not installed if version higher than in a release pocket

[Jean-Baptiste Lallement]

While trying to find a workaround for bug 1921862, we tried building a rootfs of Ubuntu Desktop from a PPA that contains a new version of ubiquity and zsys in focal.

Current version in the archive:
 ubiquity | 20.04.15 | focal
 ubiquity | 20.04.15.11 | focal-updates
 zsys | 0.4.5 | focal
 zsys | 0.4.8 | focal-updates

Versions in the PPA (https://launchpad.net/~jibel/+archive/ubuntu/ppa/+packages)
ubiquity | 20.04.15.12~ppa3
zsys | 0.4.8ubuntu1ppa1

The results of the builds are:
Without the PPA (same than an Ubuntu Desktop build without proposed)
https://launchpad.net/~jibel/+livefs/ubuntu/focal/ubuntu-archive/+build/276788

With the PPA
https://launchpad.net/~jibel/+livefs/ubuntu/focal/ubuntu-archive/+build/276827

The builds have been triggered with the API, the only difference is the metadata_override which contains the PPA:

In [67]: livefs2.requestBuild(archive = archive, distro_arch_series = das, metadata_override= {'project': 'ubuntu'}, pocket='Updates')
Out[67]: <livefs_build at https://api.launchpad.net/devel/~jibel/+livefs/ubuntu/focal/ubuntu-archive/+build/276788>

In [68]: livefs2.requestBuild(archive = archive, distro_arch_series = das, metadata_override= {'project': 'ubuntu', 'extra_ppas' : ['jibel/ppa']}, pocket='Updates')
Out[68]: <livefs_build at https://api.launchpad.net/devel/~jibel/+livefs/ubuntu/focal/ubuntu-archive/+build/276827>

(archive is the primary archive)

If you compare the 2 builds
ubiquity and zsys and in the first build but not the second.

[Steve Langasek (vorlon)]

Is this perhaps because the packages in the ppa have no Task fields set? Which can be addressed by setting them manually with XB-Task: in debian/control.

[Steve Langasek (vorlon)]

(If so, I don't think this is a livecd-rootfs bug; livecd-rootfs shouldn't be expected to override the archives wrt Task fields)

[Jean-Baptiste Lallement (jibel)]

I confirm that adding XB-Task addresses the issue and the package from the PPA is installed. However, when there is no task defined, the package from archive should be installed.