addrevision: rework generaldelta computation...
addrevision: rework generaldelta computation
The old code have multiple explicit tests and code duplications. This makes it
hard to improve the code. We rewrite the logic in a more generic way, not
changing anything of the computed result.
The final goal here is to eventually be able to:
- factor out the default fallback case "try against 'prev'" in a single place
- allow 'lazydeltabase' case to use the smarter general delta code path when
the incoming base does not provide us with a good delta.
