appstream breaks installation as it is incompatible with gnome-software

[Sebastian Unger]

The latest xenial backports version of appstream has a breaks: gnome-software (<< 3.22.5-1) in its control file, but there is no version of gnome-software > 3.22 available in any xenial repos.

This causes the installation process to break when backports are enabled.

[Sebastian Unger (sebunger44)]

Example excerpt of a debian installer log:

Feb 3 00:31:15 pkgsel: starting tasksel
Feb 3 00:31:19 in-target: debconf: unable to initialize frontend: Passthrough
Feb 3 00:31:19 in-target: debconf: (Failed to open fd 3: Bad file descriptor at (eval 19) line 3.)
Feb 3 00:31:19 in-target: debconf: falling back to frontend: Noninteractive
Feb 3 00:31:19 in-target: ^MExtracting templates from packages: 35%
Feb 3 00:31:19 in-target: ^MExtracting templates from packages: 70%
Feb 3 00:31:19 in-target: ^MExtracting templates from packages: 100%
Feb 3 00:32:23 in-target: Reading package lists...
Feb 3 00:32:23 in-target:
Feb 3 00:32:23 in-target: Building dependency tree...
Feb 3 00:32:23 in-target:
Feb 3 00:32:23 in-target: Reading state information...
Feb 3 00:32:23 in-target:
Feb 3 00:32:24 in-target: crda is already the newest version (3.13-1).

...

Feb 3 00:32:25 in-target: xz-utils is already the newest version (5.1.1alpha+20120614-2ubuntu2).
Feb 3 00:32:25 in-target: xz-utils set to manually installed.
Feb 3 00:32:25 in-target: Some packages could not be installed. This may mean that you have
Feb 3 00:32:25 in-target: requested an impossible situation or if you are using the unstable
Feb 3 00:32:25 in-target: distribution that some required packages have not yet been created
Feb 3 00:32:25 in-target: or been moved out of Incoming.
Feb 3 00:32:25 in-target: The following information may help to resolve the situation:
Feb 3 00:32:25 in-target:
Feb 3 00:32:25 in-target: The following packages have unmet dependencies:
Feb 3 00:32:25 in-target: appstream : Breaks: gnome-software (< 3.22.5-1) but 3.20.1+git20161013.0.d77d6cf-0ubuntu2~xenial1 is to be installed
Feb 3 00:32:25 in-target: E
Feb 3 00:32:25 in-target: :
Feb 3 00:32:25 in-target: Unable to correct problems, you have held broken packages.
Feb 3 00:32:25 in-target:
Feb 3 00:32:25 in-target: tasksel: apt-get failed (100)
Feb 3 00:32:25 main-menu[3385]: WARNING **: Configuring 'pkgsel' failed with error code 1
Feb 3 00:32:25 main-menu[3385]: WARNING **: Menu item 'pkgsel' failed.

[Sebastian Unger (sebunger44)]

In addition this problem causes already installed machines to REMOVE some packages on upgrade (when done using apt-get dist-upgrade)

[Matthias Klumpp (ximion)]

Easiest solution: remove the breaks on gnome-software and plasma-discover and add a revert of this upstream patch: https://github.com/ximion/appstream/commit/1e43075ccaf55dd269f2406d758e332fd95cda39

Alternatively add the apt config snippet in the new GNOME Software package version to the one in Xenial and adjust the breaks to a lower version.

[Iain Lane (laney)]

I'll fix this, but your installation process should be respecting the NotAutomatic setting of backports and not selecting this version.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Landon Thomas (lthomas)]

I've just looked at the patch to enable NotAutomatic support in apt-ftparchive: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=272557#55 If this isn't fixed soon, I'll have to either redesign our customized repo software environment or upgrade our repo server from Ubuntu 14.04 to 16.04 to have an apt version new enough to be compatible with the patch, which doesn't appear natively until zesty.

[Iain Lane (laney)]

I uploaded the fix. Let this bug know if it doesn't resolve the issue for you.

Thanks for reporting.