VMs end up without grub installed

Between working through getting dirinstall to build Xen VMs and upgrades
to FAI I appear to have broken FAI PXE builds and could use some help.

The FAI server is a Ubuntu 18.04 system with a Buster nfsroot.  The
Ubuntu system has FAI 5.9.4 and the Buster nfsroot is 5.10.1.  The
Ubuntu host is at 5.9.4 because the newer version of FAI uses a shell
command not available in Ubuntu 18.04.  (Don't remember exactly which
one right now and I want to get this note in the mail.)

What I am seeing is the that everything on the build goes fine until
GRUP_PC/10_setup.  10_setup exists with error status of 1.  The
resulting system does not boot, well, boots to a blank screen.  Looking
at the system I see that /boot/grub/ does not contain a grub.cfg.

The grub package that is in my packages configuration is grub-pc.
The 10_setup script is setting debconf-set-selections in /target
and then running dpkg-recongfigure grub-pc.  When I do this manually
the command returns without creating a grub.cfg.  Maybe this should
be update-grub?

So, if someone has seen a similar problem please let me know how you
solved the issue.  Otherwise, I would appreciate a couple pointers
for things I should be looking at.

Thanks in advance,

Bill

-- 
Bill MacAllister <[email protected]>