.arcconfig

revlogdeltas: move special cases around raw revisions in finddeltainfo

The method already contains logic for no-diff cases. Having everything in the
same place is more consistent and unlocks other code improvements.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}