.arcconfig

nodemap: fix missing r-prefix on regular expression

Looking at this regular expression, it's pretty obvious from reading
it that it wanted to match literal ., but since the r was missing on
the pattern it was matching any character. I guess we're just lucky
nothing bad happened as a result. This was automatically fixed by
pyupgrade, but I split it out into its own change because it seemed
important.

Differential Revision: https://phab.mercurial-scm.org/D8254

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