revlog: use the new sidedata map return in the sidedata method So far things, seems logical. Differential Revision: https://phab.mercurial-scm.org/D6810

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