Fetcher cannot serialize unicode pages

[GiovanH]

In pages with unicode symbols, self._response2namespace(response).dump(self._url2path(url)) fails with

UnicodeEncodeError: 'charmap' codec can't encode           
                    character '\u2696' in position 6182: character             
                    maps to <undefined>

.dump() seems to be trying to save a yaml object with a default encoding, when it needs to force utf-8.

[vokimon]

Could you provide an example of url please?