If you apply my decorate2.patch, configure mm_cfg.py, restart mailman, and you send UTF-8/8bit mail to a ISO-8859-1 list, then Decorate.py first check the order of mcset/lcset and finds you have set mcset first, try to decorate the message with heder/footer in mcset (UTF-8) and because cs==mcset, check the cte and set cs.body_encoding=None. You will happily get UTF/8bit message from the list.
If you apply my decorate2.patch, configure mm_cfg.py, restart mailman, and you send UTF-8/8bit mail to a ISO-8859-1 list, then Decorate.py first check the order of mcset/lcset and finds you have set mcset first, try to decorate the message with heder/footer in mcset (UTF-8) and because cs==mcset, check the cte and set cs.body_ encoding= None. You will happily get UTF/8bit message from the list.
Am I wrong ?