Victor: yes, I was thinking that when I added that comment but forgot to come back to it.  Thanks for spotting that.

Another thing I forgot about yesterday is that I activated the commented out statements that do linesep transformations on the binary file data.  I'm guessing those were commented out when the module was converted to using text files, since the text file would do the transformation itself.  Your patch left them commented out, and the tests passed on Windows.  If the tests *still* pass on windows with them uncommented, then that will prove that, like the old email tests, the line ending variations aren't really being tested.

But, the important thing here is that I haven't run the tests on Windows yet, and that certainly needs to be done.