Cause: Previous versions of package accepted the tested RHEL image version 6.6. However, this version was soft-deprecated in favor of RHEL 6.7 (which has now been tested successfully with this package).
Consequence: Current image version was rejected by script preconditions (though it succeeded if preconditions were forcibly ignored.)
Fix: Opened precondition to accept any RHEL 6 guest image.
Result: Current RHEL 6 guest image passes precondition and builds images successfully.