wav2vec everstore support fix

Summary: fixes some merge issues that prevented wav2vec from training properly

Reviewed By: myleott

Differential Revision: D16981120

fbshipit-source-id: cad39aaf2f44daabcbafe7b4e8735d055b3842a7

train.py

@@ -117,6 +117,10 @@ def train(args, trainer, task, epoch_itr):
     valid_subsets = args.valid_subset.split(',')
     max_update = args.max_update or math.inf
     for i, samples in enumerate(progress, start=epoch_itr.iterations_in_epoch):
+        samples = [s for s in samples if len(s) > 0]
+        if len(samples) == 0:
+            continue
+
         log_output = trainer.train_step(samples)
         if log_output is None:
             continue