Should this be `IS_WINDOWS`? The only reason it shouldn't (I think) is if Sage can be run and tested on Windows through Cygwin (which would give `os.name == 'nt'` and so `IS_WINDOWS == True`, but `sys.name = 'cygwin'` so the code block runs). The next question would be, can the other sections triggered by `IS_WINDOWS` would work in Cygwin.