tests/test-dirstate-backup.t

largefiles: add support for 'largefiles://' url scheme

This changesets allows Mercurial to transparently download content from the
configured largefile store. This handle all authentication and largefile
protocol details.

The target usecase is to leverage largefile infrastructure for clone bundle. See
next changeset for details

Set up

  $ hg init repo
  $ cd repo

Try to import an empty patch

  $ hg import --no-commit - <<EOF
  > EOF
  applying patch from stdin
  abort: stdin: no diffs found
  [255]

No dirstate backups are left behind

  $ ls .hg/dirstate* | sort
  .hg/dirstate