'Check instance health, should return status object or None under
certain error conditions.'

def _get_instance_health(self, lb):

    try:
        status = lb.get_instance_health([self.instance_id])[0]
    except boto.exception.BotoServerError as e:
        if (e.error_code == 'InvalidInstance'):
            return None
        else:
            raise
    return status
