I'm not sure what's going on here, but we need to limit these lines
to a Python 3.6 version range check because Python 3.5's behavior
is subtly different. We already had some lines conditional on
Python 3.5+ and 3.6+. I guess whoever made this test pass on 3.6+
forgot to test on 3.5+.
With this change, the test harness is clean on Python 3.5 on Linux
on my machine.