.arcconfig

revset-benchmark: use a generic revset to test `heads(commonancestors())`

This allow to benchmark revset performance in other repositories than just
the mercurial one.

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