Make RHEL build properly
Make RHEL build properly

build.py -b rhel -t [rdo|rhos|source|binary]

The last patch for this didn't quite fix the problem properly as
it only permitted RHOS builds.

backport: liberty

Change-Id: I27eed202560adce450c07d043cc224e7a6c6bbf6
Closes-Bug: #1513088

coolsvap/kolla,negronjl/kolla,GalenMa/kolla,mandre/kolla,intel-onp/kolla,dardelean/kolla-ansible,tonyli71/kolla,openstack/kolla,rahulunair/kolla,coolsvap/kolla,GalenMa/kolla,dardelean/kolla-ansible,mrangana/kolla,limamauricio/mykolla,limamauricio/mykolla,openstack/kolla,mandre/kolla,limamauricio/mykolla,coolsvap/kolla,dardelean/kolla-ansible,intel-onp/kolla,mandre/kolla,toby82/kolla,nihilifer/kolla,negronjl/kolla,negronjl/kolla,stackforge/kolla,toby82/kolla,toby82/kolla,stackforge/kolla,nihilifer/kolla,stackforge/kolla,rahulunair/kolla,mrangana/kolla,tonyli71/kolla