Ensure we collect failed reverted state

[Didier Roche-Tolomelli]

Two kind of datasets we should collect in the GC:
- root and children datasets if reverting failed (initramfs cloned -> failed in generator)
- states that don’t have a valid LastUsed

To evaluate:
- main dataset for a machine is never cleaned up, so ok
- only consider (and ensure that we set this) zsys / datasets and children
- maybe consider creation date if no LastUsed set? (to avoid race between creation, like on another machine and immediate collect)

[Launchpad Janitor (janitor)]

This bug was fixed in the package zsys - 0.4.3

---------------
zsys (0.4.3) focal; urgency=medium

  [ Jean-Baptiste Lallement ]
  [ Didier Roche ]
  * Fix GC collection of failed revert or incomplete boots and add tests for
    them (LP: #1870057, #1870054)
  * Account filesystem datasets in GC bucket policy budget, as it was leading
    to under budget results once cleaned up.
  * Fix warning when mounting source is set to default (LP: #1870052)
  * Fix some issues in go-libzfs:
    - it was not assigning the correct dataset type, leading to a segfault
      if the user has a zfs volume in a pool.
    - Perf enhancements by only loading our needed properties to reduce the
      amount of C performed calls.
  * Enhance apt hook:
    - Only display output and errors if running on ZFS systems
      (LP: #1868523, #1870304).
    - Suppress the 20 minutes grace period and only prevent multiple snapshots
      when unattended-upgrades is running.
  * Transition from 19.10: change the userdata user properties on first boot
    for machines installed from 19.10 without zsys installed.
  * Add apport hook.
  * Fix various mispells, simplify some code and remove some ineffective
    assignements.
  * Fix error message typos.
  * Fix generator check on CI, update bug template and update CI to use Go 1.14
    in preparation of focal switch to 1.14.

 -- Didier Roche <email address hidden> Wed, 08 Apr 2020 14:42:21 +0200