adapted from debian-upstream [0] commit
53276c973c5e69f75b43371a6c94adc5d9dcfec0
(the systemd sequence is enabled by default since debhelper v10 - see
debhelper(7))
[0] https://salsa.debian.org/zfsonlinux-team/zfs.git
Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>