Try to fix broken Unicode in some messages

I've honestly no idea why this is needed. As far as I can see, $text has
the same contents, utf8::is_utf8($text) returns 0, and utf8::valid()
returns 1, in both 'working' and 'broken' cases. [So the if{} isn't even
really necessary here.]

Oh well. I'm not the first one, nor probably the last one, to be
confused by this. But at least I can hack around it.