If it looks like UTF-8 (either nl_langinfo or locale variables),

If it looks like UTF-8 (either nl_langinfo or locale variables),
think UTF-8, embrace your inner UTF-8, as suggested by Larry.
(And as suggested by Markus Kuhn.)

While we are at it, document also the case of
mixed hash keys as a known potential troublemaker.
(Since it's locale-related, sometimes.)

p4raw-id: //depot/perl@15350