disable broken test case on Windows

[compnerd]

This test triggers an assertion failure. It is unclear why this is currently being parsed improperly.

[compnerd]

@tomerd wanted to make progress on adopting System for SPM, and we need to resolve this (along with the other test failures). I've since paged a lot of the path processing out, but I think that this particular case should be parsed as \\foo\bar, baz (I will verify that).

[glessard]

@swift-ci please test

[glessard]

I would like to unblock the rest of Windows testing, so I am inclined to merge this with the addition of a link to issue 137.

[glessard]

@swift-ci please test