tests/test-empty-dir.t

phabricator: allow local revisions to be specified with `phabupdate`

It's way easier and less error prone to specify a revset after importing a
series than to manually type in a series of Differentials.

Unlike most revision oriented commands, this requires the `--rev` option
explicitly because the existing `DREVSPEC` doesn't need to have the leading 'D',
and therefore the meaning is ambiguous.  I wouldn't have a problem giving
precedence to the local revnum, but `phabread` and `phabimport` also use
DREVSPEC, and local revisions make no sense there.  I would be fine with
modifying that definition to require the leading 'D', but I'm not sure how many
people are used to not specifying it.

Differential Revision: https://phab.mercurial-scm.org/D9356

  $ hg init

  $ echo 123 > a
  $ hg add a
  $ hg commit -m "first" a

  $ mkdir sub
  $ echo 321 > sub/b
  $ hg add sub/b
  $ hg commit -m "second" sub/b

  $ cat sub/b
  321

  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cat sub/b 2>/dev/null || echo "sub/b not present"
  sub/b not present

  $ test -d sub || echo "sub not present"
  sub not present