'make release' on ZFS filesystem fails: chflags: operation not permitted

[O. Hartmann]

I followed the steps making a release on FreeBSD 8.0-RC2/AMD64 on my
box, the target CHROOTDIR is located on a ZFS volume. I searched the
list for a solution, but did not find any.
sysctl kern.securelevel shows
kern.securelevel: -1

Is there any solution? I guess those with complete ZFS infrastructure
will not be able performing a make release, or do they?

Thanks in advance,
Oliver