For migrants who’ve planned to immigrate to Europe, one of the last stops is an expanse of olive trees on North Africa’s Mediterranean coastline. But in Tunisia, less than 100 miles (161 kilometers) from the Italian islands that form the European Union’s outermost borders, for many that dream has become a nightmare. Under black tarps covered with blankets and ropes, men, women and children seek shelter from sunlight and wait for their chance to board one of the iron boats that paid smugglers use to transport people to Italy. Having fled war, poverty, climate change or persecution, they find th…