This extends the changes done 01cd702ee3
to another test case and so makes as much sense as the other commit.
It's still not clear what's really going on here as, somehow, this test
passed under AppVeyor before, which shouldn't have been happening if the
explanation in that commit message was correct. And it also doesn't
explain why did it suddenly fail after a completely unrelated change,
see https://ci.appveyor.com/project/wxWidgets/wxwidgets/build/2502/job/l24gc2j0j7h7huxl
22e14e7c7b