BERLIN (Reuters) - European Union chief Brexit negotiator Michel Barnier said on Wednesday that the bloc had to be, and was, united in dealing with Britain on its withdrawal from the bloc and warned that failure to reach agreement would be very bad.  No deal would be a very bad deal,  Barnier said, switching from French to English in a speech to Germany s BDA employers association. It was his third speech to a German audience on Brexit in the day so far.  Barnier also said he hoped to have made progress on the principles of Britain s divorce from the EU by next week and that London knew it could not have one foot in the single market and one foot out of it. 