Error when trying to write unicode xml to zipfile

["Martin v. Löwis"]

> Unless, obviously, you were serialising to a non-utf8 encoding. But since the
> "toxml()" method seems to return unicode here (which sounds surprising), I
> expect it a) to provide no XML declaration at all or b) to be broken anyway.

Or c) the user forgot to specify the encoding= parameter in toxml().

Regards,
Martin