Some IRC discussion about what contributors should do while this is unresolved, and the bigger plan for comprehensively addressing this:

01:53 < ned_deily> jesstess, saw your nosy on Issue17496.  Beware that it's really a can of worms and definitely was misclassified as easy.  Lots of edge cases, some not discussed in the issue.
03:01 < jesstess> ned_deily: can you update the ticket with edge cases not yet discussed? The issue is making life hard for some of our interns, so I'd love to see some progress on it.
03:02 < jesstess> ned_deily: I also found ronaldoussoren's conclusions hard to follow. I think a re-statement of what the best solution for the problem is would be really helpful, if you have opinions on it.
03:04 < ned_deily> jesstess, can you say how it is causing problems?
03:08 < jesstess> ned_deily: They are working on Tkinter tickets, and their primary development platform happens to be OSX, where the tests are getting skipped. One has set up a Linux VM already, which is fine, but it's a confusing issue to hit for new contributors and they also want to have the confidence that changes and new tests pass on OSX before submitting patches for review.
03:09 < ned_deily> jesstess, OK.  Alas, Tk is a bit of a problem on any platform and it's pretty much a mess on OS X.
03:15 < ned_deily> jesstess, Currently, there are three different variants of Tk in use on OS X.  And the most commonly used variant, the Cocoa Tk 8.5, is still relatively new and has had major bugs (still present in the version shipped by Apple in OS X) and has variations from minor release to minor release.
03:20 < ned_deily> jesstess, The plan is to make things a lot easier to test by making it easier to use a custom-built Tk for OS X.  In the meantime, there really is no easy way around things.  Fixing #17496 by  itself won't allow testing on OS X. 
03:20 < ned_deily> jesstess, For the time being, I would suggest just testing as best as possible on whatever platforms one can and submitting the patches.