[Checkins] [zopefoundation/transaction] dff1c9: try to increase test coverage

[Dieter Maurer]

  Branch: refs/heads/abort_hooks_#77
  Home:   https://github.com/zopefoundation/transaction
  Commit: dff1c948ae9f7a2ef2f869bd1a35afc994ef1776
      https://github.com/zopefoundation/transaction/commit/dff1c948ae9f7a2ef2f869bd1a35afc994ef1776
  Author: dieter <dieter at handshake.de>
  Date:   2019-06-19 (Wed, 19 Jun 2019)

  Changed paths:
    M transaction/_transaction.py
    M transaction/tests/test__transaction.py

  Log Message:
  -----------
  try to increase test coverage