Drop the dep on preupgrade
    
    Preupgrade is getting retired and is replaced by fedup in F18+. There is
    still a soft dep on /usr/share/preupgrade/releases.list: PackageKit's
    yum backend reads that file to decide if it should do distro upgrades.
    However, that file as shipped in the preupgrade rpm is severely out of
    date and isn't really useful any more in its current form.