Installer forgets boot blocks?

[apologies if a duplicate post]

Selecting "use existing partitions" seems to cause the
installer to forget to add the necessary boot magic.

To repeat:
   create a set of (MBR) partitions using disklabel at shell prompt
   invoke installer
   specify mount points (and newfs) for each
   install system
   reboot
"No boot device"

If this is intended behavior, perhaps a line of text in the
installer to remind the user of steps HE is expected to perform?

[Verified the system DOES work with this "use existing partitions"
option NOT exercised.]

The "clone external partitions" is a nice feature ("Gee, I can
just pull the disk out of the EXISTING 9.1 system and clone
those!").  Except it SIGSEGV's no matter what I try (one
partition, two partitions, before, after, etc.).  Keep in
mind this is cloning an existing 9.1R that had previously
been installed on THIS box.