Root mount from ZFS takes forever...literally.

[Pawel Tyll]

>> Boot process "hangs" on Trying to mount root from zfs:tank/root - I
>> can import the pool from alternate boot source (PXE), and access files
>> fine, but I can't finish booting the system from ZFS.
> What messages do you have on screen when this happens?
> Can you upload a screenshot somewhere and post a link?
Just mounting root, and nothing happens. System is responsive,
attaching/detaching USB keyboard generates messages, and hitting
alt+ctrl+del correctly reboots the system.

After messing around with fstab (added / entry, bit redundant with
loader.conf vfs.root.mountfrom entry) it started to working again, but
I can't repeat it now by removing this. Too bad I didn't take a
snapshot before fixing :(

Strange. :)