.arcconfig

largefiles: walk history in ascending order while downloading all lfiles

I don't think the order matters. Maybe it's purely because of the use of
walkchangerevs(), which was originally designed for "hg log" command.

Surprisingly, the number of objects fetched in test-largefiles.t has changed.
According to the --verbose output, the order of the following fetches flipped
and the latter got deduplicated.

  getting large3:eb7338044dc27f9bc59b8dd5a246b065ead7a9c4
  found eb7338044dc27f9bc59b8dd5a246b065ead7a9c4 in store
  getting sub/large4:eb7338044dc27f9bc59b8dd5a246b065ead7a9c4
  found eb7338044dc27f9bc59b8dd5a246b065ead7a9c4 in store

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