Since Britain voted to leave the European Union, U.K. officials have had one message: Brexit means Brexit. Now they have EU leaders’ reply: And it’s going to hurt. The prime minister of Malta, whose country is about to assume the EU presidency, is the latest leader to dash Britain’s hopes of an easy divorce, signaling that the 27 other nations will drive a hard bargain. Joseph Muscat told the BBC that “there will not be a situation when the U.K. has a better deal than it has today.” “In the U.K. it’s fair game to bash Brussels and then you...