Hard drive install only uses .iso files and not mirrored repo?!

[Bruno Wolff III]

I have only one x86_64 box available to test installs with. I tried using
buildinstall to see if I got a later version of anaconda that way (once
upon a time I believe that anaconda on the images was a day behind). My
understanding is that I need to run that on the same architecure (at least
without learning to use mock) so I used one disk for the simple install
(that doesn't trigger the mkinitrd problem with raid/luks) and was going to
to use the other for a practice install.
Unfortunately when I tried using the new netinst.iso none of the install
options applied. The hard drive install expected the images wrapped up
in an iso file instead of being available more directly and the local CD/DVD
option wouldn't let me do something similar for a hard drive (I figured that
wasn't likely to work) because I didn't get to specify a device. The URL
and NFS options won't work either as the file isn't available over the
network.
So I would either need to make an iso image out of the repo or copy the
repo (actually just the images, as I have the repo locally on another machine
already) and do a network install.
It's probably rare that people have the images on the same machine they
are installing to, but it might be nice to provide someway to use a repo
mirror on a hard drive at some future point. (Not now, I have a lot of other
stuff work first relating to installs.) The set of people I would expect this
to help are ones mirroring rawhide on their current stable version of Fedora,
doing test installs of rawhide on to the same box in other partitions.