tests/test-backwards-remove.t

bookmark: complexity pull-push test to have deeper tree

This changeset only touch test.

The previous test was correct, it tested that the successors of an old bookmark
position was seen as a valid destination for bookmark.

However, a newer version is made for two reason:

(1) The new test check further. It check that the descendant of the successors
    is a valid destination

(2) An ever more complexe test is needed to validate a future fix to issue 3680
    Splitting complexification of the test and actual bugfix help to reduce the
    noise in the bugfix changeset. Issue 3680 is NOT fixed by this changeset.

  $ hg init
  $ echo This is file a1 > a
  $ hg add a
  $ hg commit -m "commit #0"
  $ ls
  a
  $ echo This is file b1 > b
  $ hg add b
  $ hg commit -m "commit #1"
  $ hg co 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

B should disappear

  $ ls
  a