I just ran `zypper dup` on a (nearly) current Tumbleweed system and got
the following error message:

  Installing: arpwatch-2.1a15-165.1.x86_64 ....................... 
  Additional rpm output:
  Updating /etc/sysconfig/arpwatch ...
  Failed to try-restart arpwatch@.service: Unit name arpwatch@.service is
missing  the instance name.
  See system logs and 'systemctl status arpwatch@.service' for details.

systemctl status arpwatch@.service gives:

  Failed to get properties: Unit name arpwatch@.service is neither a 
  valid invocation ID nor unit name.

Bug ID	1135319
Summary	Upgrading arpwatch: Failed to try-restart arpwatch@.service: Unit name arpwatch@.service is missing the instance name.
Classification	openSUSE
Product	openSUSE Tumbleweed
Version	Current
Hardware	x86-64
OS	Other
Status	NEW
Severity	Normal
Priority	P5 - None
Component	Basesystem
Assignee	bnc-team-screening@forge.provo.novell.com
Reporter	gp@suse.com
QA Contact	qa-bugs@suse.de
Found By	---
Blocker	---