Except for crypt, all the modules labeled 'Unix' or 'Linux' on the module index https://docs.python.org/3/py-modindex.html are absent from /Lib on Windows.  'import xyz' fails with "ImportError: no module named 'zyz'".  (I presume the same is true on unix for Windows-only modules.) 

However, crypt is present, and 'import crypt' fails with "...'_crypt'", leading one to think that the C accelerator should be present but is not. Assuming that _crypt should (cannot) not be present, please add crypt to the list of modules omitted from the Windows installer, however this is done. And if 'unix-only' is obsolete and _crypt should be present, please fix this instead. ;-)

This is 3.x issue only, as crypt is not present in my Windows 2.7.10 /Lib.  The fact that is was somehow added to some 3.x prompted me to look and see if there is anything useful without _crypt present.  I think not.