Issue #23696: Remove test on ZipImportError.__context__ because the context is

None on Windows.

When the file is not readable, the error occurs at open on UNIX. On Windows,
the error only occurs at the first operation on the open file. It would require
to many changes to set __context__ to an OSError for all file operations, for a
little benefit (__context__ is almost never used).

Lib/test/test_zipimport.py

@@ -453,7 +453,6 @@ class BadFileZipImportTestCase(unittest.TestCase):
 
             with self.assertRaises(zipimport.ZipImportError) as cm:
                 zipimport.zipimporter(TESTMOD)
-            self.assertIsInstance(cm.exception.__context__, PermissionError)
         finally:
             # If we leave "the read-only bit" set on Windows, nothing can
             # delete TESTMOD, and later tests suffer bogus failures.