.arcconfig

typing: consolidate "if not globals():" trick

Removes redundant inline comments. I think pycompat is good place to host
this kind of constants.

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