Adding multiple rounds of reshard shuffle

                   metadata_rows=metadata_rows,

                   verbosity=self.verbosity)

  def reshard_shuffle(self, reshard_size=10):

  def reshard_shuffle(self, reshard_size=10, num_reshards=3):

    """Shuffles by resharding, shuffling shards, undoing resharding."""

    #########################################################  TIMING

    time1 = time.time()

    #########################################################  TIMING

    for i in range(num_reshards):

      orig_shard_size = self.get_shard_size()

      log("Resharding to shard-size %d." % reshard_size, self.verbosity)

      self.reshard(shard_size=reshard_size)