Fix gating for find_unused_parameters

Summary: Pull Request resolved: https://github.com/fairinternal/fairseq-py/pull/600

Differential Revision: D15469322

Pulled By: myleott

fbshipit-source-id: fdefa8efbb10e48b2a04a6bc10404fd2f3f21ecf

fairseq/models/distributed_fairseq_model.py

@@ -36,7 +36,6 @@ def DistributedFairseqModel(args, model):
             output_device=args.device_id,
             broadcast_buffers=False,
             bucket_cap_mb=args.bucket_cap_mb,
-            find_unused_parameters=args.find_unused_parameters
         )
         # Maintain backward compatibility
         if 'check_reduction' in inspect.getargspec(ddp_class)[0]: