convert: correctly convert paths to UTF-8 for Subversion The previous code using encoding.tolocal() only worked by chance in these situations: * The string is ASCII: The fast path was triggered and the string was returned unmodified. * The local encoding is UTF-8: The source and target encoding is the same. * The string is not valid UTF-8 and the native encoding is ISO-8859-1: If the string doesn’t decode using UTF-8, ISO-8859-1 is tried as a fallback. During `hg convert`, the local encoding is always UTF-8. The irony is that in this case, encoding.tolocal() behaves like what someone would expect the reverse function, encoding.fromlocal(), to do. When the locale encoding is ISO-8859-15, trying to convert a SVN repo `/tmp/a€` failed before like this: file:///tmp/a%C2%A4 does not look like a Subversion repository to libsvn version 1.14.0 The correct URL is `file:///tmp/a%E2%82%AC`. Unlike previously (with the ISO-8859-1 fallback), decoding the path using the locale encoding can fail. In this case, we have to bail out, as Subversion won’t be able to do anything useful with the path.