removal of priority changed packages breaks builds of the core snap

Bug #1678042 reported by Oliver Grawert on 2017-03-31
This bug affects 1 person
Affects Status Importance Assigned to Milestone
live-build (Ubuntu)
Adam Conrad
Adam Conrad

Bug Description

Impact: core builds fail

Fix: simplify demotion removals

Testcase: rebuild ubuntu core snap and confirm build

Regression Potential: low as builds do not work at the current time


the fix for bug 1668847 seems to cause a removal of systemd-sysv (and installation of upstart) in the ubuntu core snap builds, which makes teh build fail now.

a log of the last successful build of the core snap:

a log of a current failing build:

it removes locales properly but then tries to also remove systemd-sysv in the lb_chroot_archives step

Oliver Grawert (ogra) on 2017-03-31
Changed in live-build (Ubuntu):
importance: Undecided → Critical
Andy Whitcroft (apw) wrote :

The image fails to build because we attempt to remove the systemd-sysv from the system. We do this because there is a newer version of systemd-sysv in an applied PPA for this build and that version is marked as Priority: important.

  $ apt-cache show systemd-sysv | egrep Priority\|Version
  Priority: important
  Version: 229-4ubuntu16+ppa2
  Priority: required
  Version: 229-4ubuntu16
  Priority: required
  Version: 229-4ubuntu10
  Priority: required
  Version: 229-4ubuntu4

This leads us to attempt to remove the package. The removal only deletes that one package so it is deemed removable and all hell breaks loose. The removal of this package triggers a pile of installations of new packages presumably for dependencies with alternatives which are satisfiable. In this case with a complete switch to upstart.

I believe there are two main bugs in this code. Firstly we should only be taking into account the latest version available for Priority: detection; otherwise we could switch a package back to required and it would still be removed (though in this case the removal is valid based on priority). Secondly we should not be only considering removals when testing the apt-get remove we should also consider whether its removal triggers installation of new packages; this latter implies there is a dependency but an alternative could be found.

Andy Whitcroft (apw) wrote :

Potential (untested) debdiff to fix these two issues. It almost cirtainly should be merged with the base patch and not applied as is.

tags: added: regression-update
Changed in live-build (Ubuntu):
assignee: nobody → Andy Whitcroft (apw)
Andy Whitcroft (apw) wrote :
Adam Conrad (adconrad) on 2017-03-31
Changed in live-build (Ubuntu):
assignee: Andy Whitcroft (apw) → Adam Conrad (adconrad)
Changed in live-build (Ubuntu Xenial):
assignee: nobody → Adam Conrad (adconrad)
importance: Undecided → Critical

Hello Oliver, or anyone else affected,

Accepted live-build into xenial-proposed. The package will build now and be available at in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See for documentation on how to enable and use -proposed.Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, and change the tag from verification-needed to verification-done. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed. In either case, details of your testing will help us make a better decision.

Further information regarding the verification process can be found at . Thank you in advance!

description: updated
Changed in live-build (Ubuntu Xenial):
status: New → Fix Committed
tags: added: verification-needed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package live-build - 3.0~a57-1ubuntu29

live-build (3.0~a57-1ubuntu29) zesty; urgency=medium

  * Drop ubuntu-debootstrap-demotions.patch, this should have been a
    one-time hack for xenial demotions, not a feature (LP: #1678042)

 -- Adam Conrad <email address hidden> Fri, 31 Mar 2017 05:52:24 -0600

Changed in live-build (Ubuntu):
status: New → Fix Released
Steve Langasek (vorlon) wrote :

Oliver, I believe we can release this to xenial-updates as soon as you verify that an ubuntu-core build with -proposed enabled works with this change.

Oliver Grawert (ogra) wrote :

long done :)

tags: added: verification-done
removed: verification-needed
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package live-build - 3.0~a57-1ubuntu25.3

live-build (3.0~a57-1ubuntu25.3) xenial; urgency=medium

  * ubuntu-debootstrap-demotions.patch: Hard-code the removals instead of
    trying to play fancy games with detection of demotions (LP: #1678042)

 -- Adam Conrad <email address hidden> Fri, 31 Mar 2017 05:30:01 -0600

Changed in live-build (Ubuntu Xenial):
status: Fix Committed → Fix Released

The verification of the Stable Release Update for live-build has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

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