[issue20679] 3.4 cherry-pick: 587fd4b91120 improve Enum subclass behavior

[Ethan Furman]

Changes by Ethan Furman <ethan at stoneleaf.us>:


----------
Removed message: http://bugs.python.org/msg211739

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue20679>
_______________________________________