I should note that I did not have to kill systemctl to get the upgrade to finish:
Setting up ifupdown (0.8.30) ...
insserv: Service mountkernfs has to be enabled to start service networking
insserv: Service urandom has to be enabled to start service networking
insserv: warning: current start runlevel(s) (empty) of script `networking' overrides LSB defaults (S).
insserv: warning: current stop runlevel(s) (0 6 S) of script `networking' overrides LSB defaults (0 6).
insserv: Service mountkernfs has to be enabled to start service networking
insserv: Service urandom has to be enabled to start service networking
insserv: warning: current start runlevel(s) (empty) of script `networking' overrides LSB defaults (S).
insserv: warning: current stop runlevel(s) (0 6 S) of script `networking' overrides LSB defaults (0 6).
Created symlink /etc/systemd/system/network-online.target.wants/ifupdown-wait-online.service → /lib/systemd/system/ifupdown-wait-online.service.
Job for ifupdown-wait-online.service failed because the control process exited with error code.
See "systemctl status ifupdown-wait-online.service" and "journalctl -xe" for details.
Job for ifupdown-wait-online.service failed because the control process exited with error code.
See "systemctl status ifupdown-wait-online.service" and "journalctl -xe" for details.
Setting up libva2:amd64 (2.1.0-1) ...
Processing triggers for siduction-dynamic-dms (2016.01.31) ...
Processing triggers for libc-bin (2.26-6) ...
Setting up libva-drm2:amd64 (2.1.0-1) ...
Processing triggers for systemd (237-3) ...
Setting up libjack-jackd2-0:amd64 (1.9.10+20150825git1ed50c92~dfsg-6) ...
Processing triggers for man-db (2.8.1-1) ...
Setting up libtcl8.6:amd64 (8.6.8+dfsg-3) ...
Setting up libva-x11-2:amd64 (2.1.0-1) ...
Setting up libx265-151:amd64 (1:2.7-dmo1) ...
Setting up libva-wayland2:amd64 (2.1.0-1) ...
Setting up libx265-dev:amd64 (1:2.7-dmo1) ...
Processing triggers for libc-bin (2.26-6) ...
Log ended: 2018-02-22 14:48:50