ESKI MOSUL, Iraq — An unarmed Sunni Arab man walked along a road in a patch of northern Iraq newly liberated from Islamic State extremists, holding a white surrender flag — a signal to Kurdish fighters that he is not a militant. Locals have swiftly shaken off the imposed Islamic lifestyle — but as Sunnis, from the same ethnic group as the militants, many are nonetheless bracing for treatment as collaborators. The Kurdish fighters struggled for months to inch ahead, backed by U.S.-led coalition air strikes. Gen.