packaging: setup: fix yum rollbackability check

The check to see if currently-installed packages will be able to be
reinstalled if we need to rollback wasn't always working.

Needs http://gerrit.ovirt.org/18310 (in otopi) to actually be able
to know if these packages are available for reinstallation.

Bug-URL: https://bugzilla.redhat.com/998921
Change-Id: I6449cf29771a6f9f6d165d6bc4dce2814fbc9a29
Signed-off-by: Yedidyah Bar David <didi@redhat.com>