tests/test-revert-unknown.t

automation: refresh requirements

I'm hitting errors installing the old version of cffi due to an
apparent issue where older versions of cffi aren't compatible with
the modern Clang I'm using. So let's upgrade packages to unbreak
things and to keep things modern.

Differential Revision: https://phab.mercurial-scm.org/D12629

  $ 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
  .hg
  a
  unknown