Except for the "Unicode bug", which was solved a bit later.

Which is not a big problem:

perlunicode

For Perls earlier than those described above, or when a string is passed to a function outside the subpragma's scope, a workaround is to always call utf8::upgrade($string)

Anyway, there is an example of node, where, thankfully, people *did not* suggested me to upgrade perl: Force ASCII regexp for all perls 5.8+ (perhaps because perl version was in post title)