.arcconfig

push: use "repo['.']" instead of old form "repo['']"

Note that this does not conflict with the commit message of my
previous patch: I found this after writing the previous patch
(besides, I very easily forget things).

Differential Revision: https://phab.mercurial-scm.org/D2965

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