5.6 bootblock install fails w/ auto-generated disklabel

The whole install process seems to proceed normally until I reach here:

"
Saving configuration files...Making all device nodes...done.
installboot: bootstrap overlaps with partition i

Failed to install bootblocks.
You will not be able to boot OpenBSD from sd0.
"

sd0 is a 9 GB SCA SCSI drive, pulled from a Sun Netra, with a c slice
of 8678.5 MB.
The automatic disklabel used slice a for / and gave it only 155.1 MB,
so I don't think
the 2 GB boot cap is even peripherally an issue, here. The i slice is 7.8 MB.

If it matters, the machine is a B1000, and I'm installing from a external SCSI
Plextor drive. (I couldn't get my purchased OpenBSD CD 1 to boot, but
downloaded .iso files seem fine.)

I've tried the install three times now, with two different hard disks,
with exactly
the same error.

Mike Hansen