Koji would need to be extended to offer such a thing. Currently, Koji does not have any logic to resolve the submitted ref to a commit/revision and store it as dedicated metadata. We do store the DistGit URL as extra data, but if you submit to Koji directly using a ref, it doesn’t dereference it to the commit, so you can easily break things.
In order to do this properly, when a ref is submitted to Koji, it needs to be resolved and stored as a direct database entry to check against. Once it exists as a database entry, it’s easy to do what you ask for as a Koji hub policy.