tests/test-revert-flags.t

tests: Add `--rhg` and `--with-rhg=<path>` options for `run-tests.py`

They are mostly equivalent to the corresponding `chg` options.
For now, many tests are still failing in this configuration.
It is *not* run on CI.

Differential Revision: https://phab.mercurial-scm.org/D10095

#require execbit

  $ hg init repo
  $ cd repo
  $ echo foo > foo
  $ chmod 644 foo
  $ hg ci -qAm '644'

  $ chmod 755 foo
  $ hg ci -qAm '755'

reverting to rev 0

  $ hg revert -a -r 0
  reverting foo
  $ hg st
  M foo
  $ hg diff --git
  diff --git a/foo b/foo
  old mode 100755
  new mode 100644

  $ cd ..