tests/test-revert-unknown.t

convert: use manifest.diff() instead of ctx.status()

mercurial_source.getchanges() seems to care about files whose nodeid
has changed even if their contents has not (i.e. it has been
reverted/backed out). The method uses ctx1.status(ctx2) to find
differencing files. However, that method is currently broken and
reports reverted changes as modified. In order to fix that method, we
first need to rewrite getchanges() using manifest.diff(), which does
report reverted files as modified (because it's about differences in
the manifest, so about nodeids).

  $ hg init
  $ touch unknown

  $ touch a
  $ hg add a
  $ hg ci -m "1"

  $ touch b
  $ hg add b
  $ hg ci -m "2"

Should show unknown

  $ hg status
  ? unknown
  $ hg revert -r 0 --all
  removing b

Should show unknown and b removed

  $ hg status
  R b
  ? unknown

Should show a and unknown

  $ ls
  a
  unknown