Description of problem: This is probably the same as https://bugzilla.redhat.com/show_bug.cgi?id=1168083 but in RHEL7 (python 2.7) the error is not the same: ERROR: The Referenced Attribute (private_subnet network_id) is incorrect. This is already fixed upstream and needs a backport.
I'm closing this issue because the improved template validation is unlikely to be backported (see https://bugzilla.redhat.com/show_bug.cgi?id=1168083 for more info). Hopefully this will be fixed upstream and it will be picked up in RHOS 7.