this goes with D799, which changes the updates image tests to
use a different updates image that works with current anaconda.
One of the updates image tests is for loading the updates image
from a hard disk, so we have a hard disk image that contains
the updates image, so that needs rebuilding with the new update
image. Simples! This is the first time we use 'imgver', I knew
it'd come in handy some time...

Apply with D799, do createhdds.py all --clean, make
sure the new image is built and the old one removed, run the
tests and make sure they work (especially install_updates_img_
local).