[Checkins] [zopefoundation/RestrictedPython] 483353: Fix breaking Python 3.9.0a5. (#194)

[Michael Howitz]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/RestrictedPython
  Commit: 483353854f1e4b90f645f7fa1dc3352379a3f995
      https://github.com/zopefoundation/RestrictedPython/commit/483353854f1e4b90f645f7fa1dc3352379a3f995
  Author: Michael Howitz <mh at gocept.com>
  Date:   2020-04-03 (Fri, 03 Apr 2020)

  Changed paths:
    M .travis.yml
    M docs/CHANGES.rst
    M setup.py
    M src/RestrictedPython/transformer.py
    M tests/transformer/test_subscript.py
    M tox.ini

  Log Message:
  -----------
  Fix breaking Python 3.9.0a5. (#194)

Handling of slices has been changed.

Co-authored-by: dieter <dieter at handshake.de>