boot problem after freebsd-update from 9.1-RC2 to 9.1-RC3

[freebsd at johnea.net]

Hello,

I recently installed a 9.1-RC2 system using gmirror with MBR, and swap in first bsdlabel.

orsbackup# gpart show
=>        63  3907029104  mirror/gm0  MBR  (1.8T)
          63          63              - free -  (31k)
         126  3907028979           1  freebsd  [active]  (1.8T)
  3907029105          62              - free -  (31k)

=>         0  3907028979  mirror/gm0s1  BSD  (1.8T)
           0           2                - free -  (1.0k)
           2    16777216             1  freebsd-swap  (8.0G)
    16777218  3890251760             2  freebsd-ufs  (1.8T)
  3907028978           1                - free -  (512B)

The drive was setup with the following commands:

orsbackup# gpart create -s MBR mirror/gm0
mirror/gm0 created
orsbackup# gpart add -t freebsd -a 4k mirror/gm0
# ignored "mirror/gm0s1 added, but partition is not aligned on 4096 bytes"
# create the bsdlabel partitions in slice 1 (s1)
orsbackup# gpart create -s BSD mirror/gm0s1
orsbackup# gpart add -t freebsd-swap -a 4k -s 8g mirror/gm0s1
orsbackup# gpart add -t freebsd-ufs -a 4k mirror/gm0s1
# put bootcode on the MBR and mark the first slice active
orsbackup# gpart bootcode -b /boot/mbr mirror/gm0
orsbackup# gpart set -a active -i 1 mirror/gm0
# put bootcode on the bsdlabel
orsbackup# gpart bootcode -b /boot/boot mirror/gm0s1


The system rebooted several times without issue. This system is a testbed for 9.1 and is not yet deployed as a production server.

I thought I'd update to 9.1-RC3, so I ran:

freebsd-update upgrade -r 9.1-RC3
freebsd-update install
reboot

The system won't boot and complains about:

"Not UFS"  "No ada0" "No boot"

Before I charge ahead with reissuing the gpart bootcode commands I thought I'd:

a) make others aware there may be issues in freebsd-update with the 9.1 release candidates

b) ask about the best way to resolve this bootloader issue.

Thanks you for any pointers in resolving this bootloader issue!

johnea