Fix for tasks that don't define args.data

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/591

Differential Revision: D15415490

Pulled By: myleott

fbshipit-source-id: c45df5f3b5327911e2c9b11642e7da2e8bb835dc

train.py

@@ -90,7 +90,7 @@ def main(args, init_distributed=False):
         if epoch_itr.epoch % args.save_interval == 0:
             checkpoint_utils.save_checkpoint(args, trainer, epoch_itr, valid_losses[0])
 
-        if ':' in args.data:
+        if ':' in getattr(args, 'data', ''):
             # sharded data: get train iterator for next epoch
             epoch_itr = trainer.get_train_iterator(epoch_itr.epoch)
     train_meter.stop()