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.
port:4:export
port:4:vaportight
port:4:import/export
FIXME: history is wrong here
port:1:1:-:eggs:import
port:1:2:+:eggs:vaportight
port:1:3:+:eggs:import/export
port:0:2:+:spam:export
port:0:1:+:spam:import
port:4:import/export