os.chmod() supports only read-only flag operations on Windows

Author: alexandrul

pyflakes/test/test_api.py

@@ -15,7 +15,7 @@
     checkRecursive,
     iterSourceCode,
 )
-from pyflakes.test.harness import TestCase
+from pyflakes.test.harness import TestCase, skipIf
 
 if sys.version_info < (3,):
     from cStringIO import StringIO
@@ -419,6 +419,7 @@ def test_invalidEscape(self):
         self.assertHasErrors(
             sourcePath, [decoding_error])
 
+    @skipIf(sys.platform == 'win32', 'unsupported on Windows')
     def test_permissionDenied(self):
         """
         If the source file is not readable, this is reported on standard