File fingerprints can tell which builds reference a given file.

What about revisions?

Given a revision, which builds happened at that revision (or changeset, for Mercurial projects) ?

Revision fingerprints would provide an answer for this question.

Remember that in the case of Mercurial changeset fingerprints, the user should only be asked about which changeset he/she wants to search for, since both build number AND job name can be derived from a changeset ID.