Comment 4 for bug 841322

Good news is that this did cause a lot of fallout on the windows buildbot at least:
<http://babune.ladeuil.net:24842/job/selftest-windows/503/>

The trivial error _win32_extract_drive_letter is easy enough to fix, however that doesn't get at the root problem which seems to be a design issue with the urlutils.split_segment_parameters functions. They are designed to remove the outside-of-url special comma syntax, but the first thing they do is try to split the url according to its rules, assuming it will ignore everything following the comma. This does not work if added suffix makes the url invalid.