.arcconfig

manifest: drop the `indexfile` from `manifestrevlog`

Since `manifestrevlog` object are not revlog (no really, they are not…) we drop
the revlog specific attribute. We need to directly access the underlying revlog
in a couple of place that already assume that we have a revlog here.

This is motivated by future change to that revlog attribute.

Differential Revision: https://phab.mercurial-scm.org/D10572

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