[Checkins] [zopefoundation/zope.testbrowser] db8ceb: Fix tests on master

[Marius Gedminas]

  Branch: refs/heads/fix-tests
  Home:   https://github.com/zopefoundation/zope.testbrowser
  Commit: db8ceb33eb669ffa872cbe530ed1529cd17c4cb0
      https://github.com/zopefoundation/zope.testbrowser/commit/db8ceb33eb669ffa872cbe530ed1529cd17c4cb0
  Author: Marius Gedminas <marius at gedmin.as>
  Date:   2019-02-05 (Tue, 05 Feb 2019)

  Changed paths:
    M docs/cookies.rst

  Log Message:
  -----------
  Fix tests on master

browser.cookies.change() helpfully makes the cookie disappear if you set
an expirationd date in the past.

We had a narrative test that tried to use a fixed future date (2019
January 1st) that is no longer a future date.

Now in a regular unit test I could do things like datetime.date.today()
and write a test that will never expire.  But this is a doctest so I'll
just shift all the dates 10 years into the future and leave the problem
for some unlucky future person down the road.

Fixes #62.