Adjust a test to work properly on Windows

Windows does things a little different than everybody else, just a
little. Just enough to be annoying in its neediness, in its desire
to make developers spend so much time on Windows that they cannot
afford to spend time doing some more useful things.

Read: here goes another Microsoft time tax.

Thanks, Jayde Jenkins, for pointing out Microsoft Windows' problems.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>