Ahead of a meeting of the 27 remaining European Union nations in Brussels on Saturday, Chancellor Angela Merkel briefed the German parliament, the Bundestag, about Germany’s strategy vis-à-vis Brexit. But at least in part, her message was aimed across the English Channel. The chancellor warned London not to expect a deal that would privilege the UK. “A third-party state cannot enjoy the same advantages or be better positioned than an EU member state,” Merkel said. “I have the feeling that some people in Britain maintain illusions in this regard. They’re wasting their time.” That line drew applause from members of...