tests/test-issue1089.t

vfs: use 'vfs' module directly in 'contrib/undumprevlog'

Now that the 'vfs' classes moved in their own module, lets use the new module
directly. We update code iteratively to help with possible bisect needs in the
future.

https://bz.mercurial-scm.org/1089

  $ hg init
  $ mkdir a
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b (glob)
  $ hg ci -m m a

  $ mkdir a b
  $ echo a > a/b
  $ hg ci -Am m
  adding a/b

  $ hg rm a
  removing a/b (glob)
  $ cd b

Relative delete:

  $ hg ci -m m ../a

  $ cd ..