Fix --reset-meters

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/756

Differential Revision: D16418302

Pulled By: myleott

fbshipit-source-id: 62495a0bff41d1741e2b09807a3b43ff2c66c8fb

fairseq/trainer.py

@@ -184,7 +184,7 @@ class Trainer(object):
 
             self.lr_step(epoch)
 
-            if 'train_meters' in extra_state:
+            if 'train_meters' in extra_state and not reset_meters:
                 self.meters.update(extra_state['train_meters'])
                 del extra_state['train_meters']