German Finance Minister Wolfgang Schäuble warned Friday that if Britain voted to leave the European Union, it wouldn’t have access to the single market like non-members Norway and Switzerland do. “That won’t work,” the veteran minister told Germany’s Der Spiegel weekly, which on Saturday plans to publish a German-English edition at home and in Britain with “Please don’t go!” on the cover. “That would require the country to follow the rules of a club which right now it wants to leave.” […] Schäuble warned that a Brexit could spark contagion in the EU, according to excerpts of the interview due...