Comment 7 for bug 1720397

On upgrades before Artful/Pike this file was not properly cleaned.
So maybe then they kept the old config with the sysV wrapper in those upgrade cases until cleaned up?

Anyway - I checked releases X to A and found that:
X - only sysv - ok
Y - only sysv - ok
Z - systemd service, disabled - bug
A - systemd service, disabled - bug

Along the placement of the default file we have in d/rules:
  dh_installinit -pqemu-system-common --no-restart-on-upgrade --error-handler=true --name=qemu-kvm
Since we have no dh --with systemd to cover automatically and formerly the generators picked it up by default as active (by considering the sysv active) this might now need something like:
  dh_systemd_enable -pqemu-system-common --name=qemu-kvm qemu-kvm.service

Given that this is broken for all of Zesty (and UCA-Ocata) time I'll mark it medium.
Depending how the testing works and if we collide with the Artful release locking down uploads the fix might be delayed a bit.