Issue #4844: ZipFile now raises BadZipFile when opens a ZIP file with an
incomplete "End of Central Directory" record.  Original patch by Guilherme
Polo and Alan McIntyre.
Added test to ensure localized calendar methods return strings and not bytes.
Issue #17041: Fix doctesting when Python is configured with the
--without-doc-strings.
#16128: clarify that instances of user-defined classes compare equal with themselves.