view .arcconfig @ 44089:bd22e90c54b3

graft: extract repo[None] to a variable

I plan to allow the caller pass in an overlayworkingctx, so this
prepares for that.

Differential Revision: https://phab.mercurial-scm.org/D7857

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