Comment # 9 on bug 1088067 from Martin Vidner

Yes, this is a problem of getting a string with an unknown/binary encoding
(ASCII-8BIT is an unfortunate name) and trying to add it to a UTF-8 string.
Probably an external program outputs Russian and we interpret it as binary
instead of as text.

Unfortunately the exception does not say which strings they are, making it
harder to identify the source of the problem. But if the problem is
reproducible, we can add more details to this specific exception class to log
the strings.