Previously, if a predicate evaluated to a match with a specific repo
rev, the rev would not be added to the expanded query. In practice,
I don't think this could ever be hit because, if a repo rev was specified,
the rev filter would apply after the predicate was evaluated as well,
returning only results that matched the predicate-evaluated repo and
the original revision-narrowed repo.
That said, there may be cases in the future where predicates can
evaluate to specific revisions of a repo, and fixing this now will save
some headaches down the road.
