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.

abort: Failed to parse .../t/.hg/hgrc
File contains no section headers.
file: .../t/.hg/hgrc, line: 1
'invalid\n'