[Checkins] [zopefoundation/Persistence] 69c98b: - fix six version conflict on Travis CI

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/Persistence
  Commit: 69c98b36fb1f5cafcb6ed19a68662ba361d571b6
      https://github.com/zopefoundation/Persistence/commit/69c98b36fb1f5cafcb6ed19a68662ba361d571b6
  Author: Jens Vagelpohl <jens at netz.ooo>
  Date:   2017-11-30 (Thu, 30 Nov 2017)

  Changed paths:
    M .travis.yml

  Log Message:
  -----------
  - fix six version conflict on Travis CI