Description of problem:
as dicussed in #fedora-devel
the idea is to pre-populate repodata on disk so things like yum provides
or repoquery runs can be done against the local cache after ststen install
regardless of network state. This recovers some of the usefulness that
fedora-rpmdb allowed to run dependancy/provides queries.

Clearly, for fc5 it would be good enough to pre-populate just base. Though it
would be great to be able to pre-populate whatever repos are active at install
time in future releases.