Systemd crashes with a simple set of target units

I cherry-picked the upstream fix. Thanks for the detailled report!

Thanks Martin! Really appreciate the quick response. :) Any ideas when this will land in one of the daily 16.04 builds?

Normally I wasn't planning an upload in the next days as there's nothing urgent queued in git, aside perhaps from this patch. But so far I only got this one report about it, thus so far I didn't consider it particularly urgent (especially as this should be simple enough to work around by setting a nonzero timeout). But there surely be another upload in the next two weeks.

This bug was fixed in the package systemd - 229-3ubuntu1

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systemd (229-3ubuntu1) xenial; urgency=medium

  * Merge with Debian unstable. Remaining Ubuntu changes:
    - Hack to support system-image read-only /etc, and modify files in
      /etc/writable/ instead.

    Upgrade fixes, keep until 16.04 LTS release:
    - systemd Conflicts/Replaces/Provides systemd-services.
    - Remove obsolete systemd-logind upstart job.
    - Clean up obsolete /etc/udev/rules.d/README.
    - systemd.postinst: Migrate mountall specific fstab options to standard
      util-linux "nofail" option.
    - systemctl: Don't forward telinit u to upstart. This works around
      upstart's Restart() always reexec'ing /sbin/init on Restart(), even if
      that changes to point to systemd during the upgrade. This avoids running
      systemd during a dist-upgrade. (LP: #1430479)
    - Provide shutdown fallback for upstart. (LP: #1370329)
    - Break lvm (<< 2.02.133-1ubuntu1) and remove our dummy /etc/init.d/lvm2
      on upgrades, as it's shipped by lvm2 now.
    - Make udev break on mdadm << 3.3-2ubuntu3, as udev's init script dropped
      the "Provides: raid-mdadm".
    - Clean up /var/log/udev on upgrade (which is written under upstart, but
      not under systemd). (LP: #1537211)
    - Migrate existing s390x network configuration to new names. (LP: #1526808)
    - systemd.postinst: Bump Version comparison for migrating the UTC setting
      from /etc/default/rcS to /etc/adjtime, to run it for upgrades to 16.04.
    - VMWare BIOS reports implausibly high onboard numbers. This got fixed in
      upstream commit 6c1e69f9. Migrate names in ifupdown accordingly.
      (LP: #1550539)

systemd (229-3) unstable; urgency=medium

  [ Martin Pitt ]
  * debian/tests/timedated: Add tests for "timedatectl set-local-rtc".
  * Be more tolerant in parsing /etc/adjtime.
  * debian/systemd.postinst: Don't fail package installation if systemctl
    daemon-reload trigger fails. This does not fix the root cause of the
    reload failures, but at least causes fewer packages to be in a broken
    state after upgrade, so that a reboot or apt-get -f install have a much
    higher chance in succeeding. (For bugs like LP #1502097 or LP #1447654)
  * debian/tests/networkd: Skip test_hogplug_dhcp_ip6 when running against
    upstream as well.
  * debian/tests/boot-and-services: Wait for units to stop with a "systemctl
    is-active" loop instead of static sleeps.
  * debian/tests/networkd: Skip DHCPv6 tests for downstream packages too. This
    is an actual regression in networkd-229, to be investigated. But this
    shouldn't hold up reverse dependencies.
  * Fix assertion in add_random(). (LP: #1554861)
  * debian/tests/boot-and-services: Don't assert on "Stopped Container c1"
    message in NspawnTests.test_service(), this is sometimes not present. Just
    check that the unit did not fail.
  * Add "adduser" dependency to systemd-coredump, to quiesce lintian.
  * Bump Standards-Version to 3.9.7 (no changes necessary).
  * Fix timespec parsing by correctly initializing microseconds.
    (Closes: #818698, LP: #1559038)
  * networkd: Add fallback if FIONREAD is not supported. (C...