polish train

tools/train.py

@@ -95,7 +95,7 @@ def main(args):
         # 1. train with train dataset
         program.run(train_dataloader, exe, compiled_train_prog, train_fetchs,
                     epoch_id, 'train')
-        if int(os.environ.get("PADDLE_TRAINERS_ID", 0)) == 0:
+        if int(os.getenv("PADDLE_TRAINER_ID", 0)) == 0:
             # 2. validate with validate dataset
             if config.validate and epoch_id % config.valid_interval == 0:
                 top1_acc = program.run(valid_dataloader, exe,