How can I make systemd stop grabbing NFS mounts?

[Tom Horsley]

I go to a lot of trouble to NOT mount NFS at boot because
many test systems here are often down and I don't want to
timeout when trying to mount things.

I can still mount things manually when I need them, but
now systemd screws up my life by saying "Ah-HA! Here's
an NFS mount! I'll make a unit for it so I can spend 10
minutes timing out when the poor fool tries to reboot
after that NFS server goes down!"

How do I make it stop? How do I get systemd to leave
NFS mounts utterly and completely alone? I DO NOT CARE
if they are properly unmounted by crossing all I's and
dotting all T's. I just want to frigging REBOOT!