view .arcconfig @ 40475:8fa26f3baf30

templater: add wrapper for a single template mapping

This can be used to nest template mappings without inserting a sequence-like
layer. See the next patch for example.

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