.arcconfig

perf: support looking up multiple revisions

The nodemap code has optimisations around the number of lookup we actually made.
As a result, being able to specify multiple revisions to look up is important
when measuring performances. One can now specify full revspecs with the --rev
arguments.

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