message: dont save the first dataset twice
diff: @@ -141,6 +141,7 @@ def selfplay(
  if idx == 0:
  ds = DataSetV2.from_positions_w_context(pwcs, pis, results)
  #TODO: this does a lot of needless copying (O(n^2))... fix eventually
  + else:
  ds.extend(DataSetV2.from_positions_w_context(pwcs, pis, results))
  fname ="{:d}-{:d}".format(int(time.time()), idx)
  with open(os.path.join(output_sgf, fname + '.sgf'), 'w') as f:
  