boot-smoke autopkgtest sometimes fails on restarting lightdm

I suspect that X.org sometimes fails to start with the dummy driver and thus lightdm restarts in a loop. But not sure about that, so for now I added a commit that outputs some additional debugging information in that case:

  http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/commit/?id=2c61cc987

I hope http://anonscm.debian.org/cgit/pkg-systemd/systemd.git/commit/?id=4a5b0df05 will do the trick. Let's see how it performs with the next few upstream pull requests.

This bug was fixed in the package systemd - 229-5ubuntu1

---------------
systemd (229-5ubuntu1) yakkety; urgency=medium

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

systemd (229-5) unstable; urgency=medium

  * debian/tests/unit-config: Call "daemon-reload" to clean up generated units
    in between tests.
  * debian/tests/unit-config: Check that enable/disable commands are
    idempotent.
  * debian/tests/unit-config: Detect if system units are in /usr/, so that the
    test works on systems with merged /usr.
  * debian/tests/unit-config: Use systemd-sysv-install instead of update-rc.d
    directly, so that the test works under Fedora too.
  * debian/tests/unit-config: Check disabling of a "systemctl link"ed unit,
    and check "systemctl enable" on a unit with full path which is not in the
    standard directories.
  * Rename debian/extra/rules/73-idrac.rules to 73-special-net-names.rules, as
    it is going to get rules for other devices. Also install it into the
    initramfs.
  * debian/extra/rules/73-special-net-names.rules: Add DEVPATH number based
    naming schema for ibmveth devices. (LP: #1561096)
  * Don't set SYSTEMD_READY=0 on DM_UDEV_DISABLE_OTHER_RULES_FLAG=1 devmapper
    devices with "change" events, as this causes spurious unmounting with
    multipath devices. (LP: #1565969)
  * Fix bogus "No [Install] section" warning when enabling a unit with full
    path. (LP: #1563590)
  * debian/tests/cmdline-upstart-boot: In test_rsyslog(), check for messages
    from dbus instead of NetworkManager. NM 1.2 does not seem to log to syslog
    by default any more.
  * Bump Standards-Version to 3.9.8 (no changes necessary).
  * debian/tests/boot-smoke: Add some extra debugging if there are pending
    jobs after 10s, to figure out why lightdm is sometimes "restarting".
    (for LP #1571673)
  * debian/tests/boot-smoke: Configure dummy X.org driver (like in the
    boot-and-services test), to avoid lightdm randomly fail. (LP: #1571673)
  * Move Debian specific patches into debian/patches/debian (which translates
    to "Gbp-Pq: Topic debian" with pq). This keeps upstream vs. Debian
    patches separated without the comments in debian/patches/series (which
    always get removed by "pq export").
  * Don't ship an empty /etc/X11/xinit/xinitrc.d/ directory, this isn't
    supported in Debian. (Closes: #822198)
  * udev: Mark nbd as inactive until connected. (Closes: #812485)
  * On shutdown, unmount /tmp before disabling swap. (Closes: #788303)
  * debian/systemd-coredump.postinst: Do daemon-reload before starting
    systemd-coredump, as the unit file may have changed on upgrades.
    (Closes: #820325)
  * Set MAC based name for USB network interfaces only for universally
    administered (i. e. stable) MACs, not for locally administered (i. e.
    randomly generated) ones. Drop /lib/systemd/network/90-mac-for-usb.link
    (as link files don't currently support globs for MACAddress=) and replace
    with an udev rule in /lib/udev/rules.d/73-special-net-names.rules.
    (Closes: #812575, LP: #1574483)

 -- Martin Pitt <martin...