Comment # 18 on bug 924488 from Andrei Borzenkov

(In reply to Thomas Blume from comment #17)
> Can you please make sure that you add the option:
> 
> _netdev
> 
> to all nfs mounts in /etc/fstab?

It is different problem - he speaks about manual mounts, for them _netdev is
irrelevant. The problem is that with manual NFS mounts network-online.target is
not pulled in so on shutdown there is nothing to synchronize stopping of
interfaces against. I am afraid it was my mistake to order network@.service
against network-online.target instead of network.target. I cannot say what was
the reason for this. I think we need to apply suggested patch indeed.