unable to boot ZFS with gptzfsboot from an exported zpool

Hi,

is anyone else having problems booting from exported zpools when using
gptzfsboot?

I have a script creating a GPT partition on a single fresh disk setting
up zfs booting etc.
http://anonsvn.h3q.com/projects/freebsd-patches/browser/manageBE/create-zfsboot-gpt.sh?format=txt

If I export the zpool after the script is done with the setup and try to
boot the disk, zfsboot tells me "No ZFS pools located, can't boot". If I
just plug out the disk, e.g. USB, or shutdown the system without
exporting the zpool on the new disk first, it finds the zpool and boots.

My guess is a bug in sys/boot/i386/zfsboot/zfsboot.c somewhere in
probe_drive(), not sure if its in the GPT part or somewhere else.

greetings,
philipp