#After triggering the 'delete server' event via Rackspace's Web interface, I can see in the logs a failing "poweroff" command.
core@fixed-updated-1 ~ $ journalctl -f
Apr 06 12:05:12 fixed-updated-1 systemd[1]: Created slice system-systemd\x2dcoredump.slice.
Apr 06 12:05:12 fixed-updated-1 systemd[1]: Started Process Core Dump (PID 1042/UID 0).
Apr 06 12:05:12 fixed-updated-1 systemd-coredump[1043]: Resource limits disable core dumping for process 1041 (poweroff).
Apr 06 12:05:12 fixed-updated-1 systemd-coredump[1043]: Process 1041 (poweroff) of user 0 dumped core.
Apr 06 12:05:28 fixed-updated-1 update_engine[700]: I0406 12:05:28.907824   700 update_attempter.cc:493] Updating boot flags...

#The coredump meta is present, but no core dump file ("none")
core@fixed-updated-1 ~ $ coredumpctl list
Fri 2018-04-06 12:05:12 UTC    1041     0     0   6 none      /usr/bin/systemctl

#Read coredump meta.
core@fixed-updated-1 ~ $ coredumpctl info 1041
           PID: 1041 (poweroff)
           UID: 0 (root)
           GID: 0 (root)
        Signal: 6 (ABRT)
     Timestamp: Fri 2018-04-06 12:05:12 UTC (19s ago)
  Command Line: /sbin/poweroff
    Executable: /usr/bin/systemctl
 Control Group: /
         Slice: -.slice
       Boot ID: ce73beca5cc143be8bb7b77cee8840eb
    Machine ID: f2c4f6b3ef2443db91d02b4f7f44cd68
      Hostname: fixed-updated-1
       Storage: none
       Message: Process 1041 (poweroff) of user 0 dumped core.