tests/test-empty-dir.t

rebase: fix working copy location after a --collapse (issue4080)

Rebasing with --collapse would leave the working copy on the parent of the
collapsed commit, instead of on the collapsed commit.  This fixes that.  Also
fixes a few tests that already covered this area but had bad data.

This also fixes issue3716 where bookmarks are not kept across rebases with
--collapse. I updated the test to cover that case as well.

  $ 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