we can test this quite easily by placing the standard openQA
updates image in the NFS repo used for the NFS repo install
tests. We just have to copy the contents of the ISO (instead of
directly exporting the ISO loop mount as an NFS share) so we
can add this extra file.
At first I planned to combine this with the NFS repo variation
test, but when you use a remote stage2 like this it changes repo
setup such that the packaging.log line we look for to verify
the remote repo was used does not show up, and there's enough
fuzziness in how anaconda-dracut fudges inst.repo and
inst.stage2 that it's probably a good idea to test them
separately anyhow.