The on-disk FCV cannot change while a FixedFCVRegion object is in scope. This guarantee becomes redundant within DDL operations since they will refer to a specific OFCV regardless of concurrent FCV changes. To avoid improper use of FixedFCVRegion in DDL operations, we should ensure that we report an error if a FixedFCVRegion is instantiated with a version context that has an associated OFCV.