buildpackages: install createrepo package carefully
buildpackages: install createrepo package carefully

Address error message "Source '...' does not contain the desired medium" when
repos get stale.

Signed-off-by: Nathan Cutler <f9d8c66a4e898e67db786769b5b347b640e1a9a6@suse.com>

SUSE/teuthology,SUSE/teuthology,dmick/teuthology,dmick/teuthology,dmick/teuthology,ceph/teuthology,SUSE/teuthology,ceph/teuthology,ktdreyer/teuthology,ktdreyer/teuthology