Fix consoleauth/spice duplicates on RH (#1278452)

On RedHat, consoleauth and spicehtml5proxy packages has the same name
(« openstack-nova-console »), so we have a duplicate resource (see: #1278452).
In this context we can't use ensure_package of stdlib because we loose
notify/names attributes.)

Closes-bug: #1278452

Change-Id: I0141ca0233aead072a06796759d211cf1b6dc657
(cherry picked from commit 31a282a883ca8d2450195829d4e995ece699a6a7)