latest 8.0-BETA2 lost my zfs

[Danny Braniss]

it seems that the latest changes to zfs prevents zpool to see/find
the pool in /dev/ad0p4 (BTW, the pool was created under 8.0)

# gpart show
=>        34  1953525101  ad0  GPT  (932G)
          34         128    1  freebsd-boot  (64K)
         162     4194304    2  freebsd-ufs  (2.0G)
     4194466     8388608    3  freebsd-swap  (4.0G)
    12583074  1940942061    4  freebsd-zfs  (926G)

# zpool list
no pools available
# zpool import -a
# 

under 7.2, the pool is still there:

pundit-2> zfs list
NAME     USED  AVAIL  REFER  MOUNTPOINT
z       5.27G   900G    18K  /z
z/home  5.21G   900G  5.21G  /home
z/var   59.7M   900G  59.7M  /var
pundit-2> zpool list
NAME   SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
z      920G  5.27G   915G     0%  ONLINE  -