NFS Server not working without COMPAT_13

[Dirk Mast <condor2k%gmail.com@localhost>]

Hello,

I'm running 
NetBSD slug1. 4.99.62 NetBSD 4.99.62 (NSLU2_ALL) #4: Fri May 16 16:18:25
CEST 2008 
condor@black:/home/condor/net/src/sys/arch/evbarm/compile/obj/NSLU2_ALL
evbarm

on my NSLU2.

The kernel config contains:


options         NFSSERVER


but when starting mountd, it dies with this message:
Can't delete exports for / (Function not implemented)

/var/log/messages even contains:

nfsd[181]: nfssvc: Function not implemented


I then enabled COMPAT_13 in the kernel config, recompiled and booted
the new kernel and now NFS works.

I guess this is a bug and not expected behavior, or is it?