Preserve multibyte UTF-8 characters when obfuscating. This version uses the unicode 'replace' option, so non-UTF-8 encodings will still be mangled. Luckily, there aren't any of those.

# should print nothing
# should print ? b/x
? b/x
# should print A b/x
A b/x
# should forget b/x
forgetting b/x
# should print nothing