Change horizon mapping for RDO
Change horizon mapping for RDO

https://review.openstack.org/454178 changed the mapping for SUSE, and
the required adjustments in https://review.openstack.org/454230 create
a duplicated "python-horizon" package.

Change-Id: I6899cfc41b504f7d8b3ccba3b08d883feee7c32b

openstack/pymod2pkg