.arcconfig

run-tests: introduce a `HGTEST_REAL_HG` variable for test

It turns out that currently, `hg` and `which hg` can point to different things
because `hg` is an alias… This is annoying because script and pieces of test
are unknowingly using the wrong `hg`.

We will fix it in another changeset. However some test actually need to use a
real `hg` binary and not some `chg` or `rhg` equivalent. So we introduce a new
variable with the right value and we put it to us in the appropriate location.

Differential Revision: https://phab.mercurial-scm.org/D11049

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