.arcconfig

py3: format revision number as '%d' in debugrevspec

Now "hg debugrevspec" works on Python 3.

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