'Performs update on **id** index'

def _update_id_index(self, _rev, data):

    (_id, value) = self.id_ind.make_key_value(data)
    db_data = self.get('id', _id)
    if (db_data['_rev'] != _rev):
        raise RevConflict()
    new_rev = self.create_new_rev(_rev)
    self.id_ind.update_with_storage(_id, new_rev, value)
    return (_id, new_rev, db_data)
