Comment # 7 on bug 905434 from Wolfgang Cramer

This perhaps gives a hint?

Nov 15 10:21:15 wolfgang-lt nfs[2176]: Mounting network file systems ...
Nov 15 10:21:15 wolfgang-lt nm-dispatcher[2224]: mount.nfs: /mnt/backup is busy
or already mounted
Nov 15 10:21:15 wolfgang-lt nm-dispatcher[2224]: Script
'/etc/NetworkManager/dispatcher.d/nfs' exited with error status 32.
Nov 15 10:21:15 wolfgang-lt NetworkManager[2166]: <warn> (2) nfs failed
(failed): Script '/etc/NetworkManager/dispatcher.d/nfs' exited with error
status 32.

It does not appear when there are no nfs mounts in /etc/fstab. At this time,
the system is not waiting for anything yet, that happens much later.