tests/test-issue1089.t

update: fix typo/stale comment to match code

The comment about "obsolete.background" seems to have been about
obsolete.foreground ever since it was introduced in a59e575c6ff8
(update: allow dirty update to foreground (successors), 2013-04-16),
so let's change it.

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 ..