.arcconfig

tests: add b'' to config file name

Without this, things die in the bowels of the config system
due to mixing str and bytes.

# skip-blame: just b'' prefix

Differential Revision: https://phab.mercurial-scm.org/D5723

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