By Eleanor Whitehead Lagos, Nigeria – As much of the rest of the world geared up to celebrate winter holidays in December last year, a group of 54 soldiers formerly deployed to fight Nigerian Islamists stood in front of a court martial in Abuja. Among them, one young man listened in shock as the court found him guilty of mutiny and sentenced him to death by firing squad. “We did not fire on anybody. And we didn’t threaten anybody. They are just punishing us for an unknown sin,” he explained over the phone from Lagos, where the soldiers are being…