Revert useless change

Author: vstinner

Lib/test/test_tarfile.py

@@ -3949,7 +3949,7 @@ def test_realpath_limit_attack(self):
             # path fits in PATH_MAX, but it overflows when the final symlink
             # is expanded
             steps = "abcdefghijklmnop"
-            if sys.platform in ('win32', 'cygwin'):
+            if sys.platform == 'win32':
                 component = 'd' * 25
             elif 'PC_PATH_MAX' in os.pathconf_names:
                 max_path_len = os.pathconf(self.outerdir.parent, "PC_PATH_MAX")