Met/reported the same problem running fai-setup yesterday http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=682013 and there's now a reply by Bastian Neuburger suggesting that the change from dracut 0.19 to 0.20 may be causing it.
Meanwhile, I'll probably also try the live-boot alternative today...
Best regards
J Esteves
PS: Complete fai-make-nfsroot.log temporarily at
http://paste.debian.net/179776/
