.arcconfig

commandserver: pass around option to hook repo instance creation

This is necessary to wrap a repo instance so the master process will be
notified on repo.close().

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