Root ZFS: How to NOT use the whole disk

[demux]

Hi!

I try to install not using the whole didk for zfs but leave some room at the end.

I start with an empty disk and choose "Manual".
I create a GPT partition table and then I create partitionslike that:

1. Type: freebsd-boot, Size: 512kB, Mountpoint: (none), Label: pfBOOT
2. Type: freebsd-swap, Size: 2GB, Mountpoint: (none), Label: pfSWAP
3. Type: freebsd-zfs, Size: 4GB, Mountpoint: /, Label: pfROOT

Now I hit finish and after "Your changes will now be written..." >> Commit:

Failed to mount filesystem
An installation step has been aborted. Would you like to restart...

Now, I restart, delete and same starts again.

When using ufs, everything works as expected!

What do I have to do not to fill the whole disk with zfs?

Thanks,
-lutzn

Addition: Installing 2.6.0 CE

[demux]

No ideas?