Created by: ccmeteorljh

多机下报如下错误：

    train()
  File "cluster_train.py", line 134, in train
    train_loop(t.get_trainer_program())
  File "cluster_train.py", line 114, in train_loop
    fluid.io.save_inference_model(save_dir, feed_var_names, fetch_vars, exe)
  File "/usr/local/lib/python2.7/site-packages/paddle/fluid/io.py", line 629, in save_inference_model
    os.makedirs(dirname)
  File "/usr/local/lib/python2.7/os.py", line 157, in makedirs
    mkdir(name, mode)
OSError: [Errno 17] File exists: 'cluster_model/epoch_5'