def save(self, **kwargs):
        try:
            previous_build = self.app.build_set.latest()
            to_destroy = []
            for proctype in previous_build.procfile:
                if self.procfile not in proctype:
                    for c in self.app.container_set.filter(type=proctype):
                        to_destroy.append(c)
            self.app._destroy_containers(to_destroy)
        except Build.DoesNotExist:
            pass
        return super(Build, self).save(**kwargs)
dataset/ETHPy150Open deis/deis/controller/api/models.py/Build.save/swapped operands of `not in`