delta-find: stop using heuristic to determine if we are creating a snapshot This avoid assuming a changeset is a snapshot when it is actually something simpler.

delta-find: explicitly track stage of the search Being more explicit about what we are doing is going to be useful. We actually start making use of it in later changesets.

delta-find: drop some dead debug code Seems like it was never put to use, so lets simply remove it for now.

delta-find: introduce and use specialized _DeltaSearch class For now, we introduce some very simple variant, but they are still useful to display how having the class can helps keeping the simple case simple and their special case out of more advanced logic.

delta-find: introduce a base class for _DeltaSearch This prepare the introduction of specialized the class in the next changesets.

delta-find: simplify the delta checking function for snapshot Since the function is all about snapshot, we can safely use an early return and make the result simpler.