Comment # 2 on bug 955592 from Thomas Renninger

We cannot reproduce.
Can you please attach /etc/fstab with the nfs rootfs entry included.

Also modify:
/usr/lib/dracut/modules.d/95nfs/module-setup.sh
and put
set -x
at the beginning of the function cmdline()
and
set +x
at the end of the function cmdline()

and re-run:
mkinitrd -k vmlinuz-4.1.12-1-default -i initrd.new

There should be some more output now, please attach or copy and paste again.