[Checkins] [zopefoundation/Zope] 3e8664: Port the newly written tests from `branch_397` here.

[Michael Howitz]

  Branch: refs/heads/wilkes/397-allowed-attributes
  Home:   https://github.com/zopefoundation/Zope
  Commit: 3e8664ca56bcdd4f017032e4d38f129f236e9fba
      https://github.com/zopefoundation/Zope/commit/3e8664ca56bcdd4f017032e4d38f129f236e9fba
  Author: Michael Howitz <mh at gocept.com>
  Date:   2019-05-29 (Wed, 29 May 2019)

  Changed paths:
    M buildout.cfg
    M sources.cfg
    M src/Products/Five/browser/tests/test_pages.py

  Log Message:
  -----------
  Port the newly written tests from `branch_397` here.