tests/test-dirstate-backup.t

scmutil: make shortesthexnodeidprefix() use unfiltered repo

Both callers were doing this, and resolvehexnodeidprefix() was also
working on the unfiltered repo, so it makes more sense to have it all
in one place.

Differential Revision: https://phab.mercurial-scm.org/D3313

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