Comment # 1 on bug 977952 from Neil Brown

I can reproduce this on tumbleweed simply by running

 systemctl preset nfsserver

It doesn't make sense though as /usr/lib/systemd/system/nfsserver.service does
contain an [Install] section.

[Install]
WantedBy=multi-user.target


and  "systemctl enable nfsserver" works as expected.

So I think it is a systemd problem.