bisect: limit ancestors to revs topologically between good and bad revs Previously, when constructing its dict of revisions to their ancestors, bisect would populate the dict with ALL of the descendents of the good set, which is a bit silly because it is impossible for a revision that is a descendent of the minimum known bad revision to be the first bad rev. Instead it makes more sense to limit the revisions to just those topologically between the good and bad.

bisect: bypass changectx when translating revs to nodes When resolving the revset given by the user into node hashes, use the changelog to perform the translation rather than the repo object. This avoids the overhead of constructing a changectx which is immediately discarded.