Bug #1071513: don't test on Cygwin, as chmod doesn't work reliably there (http://www.cygwin.com/faq/faq_3.html#SEC41).
Bug #1071513: don't test on Cygwin, as chmod doesn't work reliably there
(http://www.cygwin.com/faq/faq_3.html#SEC41).

Also check whether onerror has actually been called so this test will
fail on assertion instead of on trying to chmod a non-existent file.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator