Support unpickle py2 NetDef object in py3 (#26147)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26147
We may try to unpickle a byte string in py3 that was pickled from py2. Therefore we need to add encoding latin1.
Reviewed By: kennyhorror
Differential Revision: D17305677
fbshipit-source-id: c0c8a51909629a65eb72bb81cccfbabaee9f8d01
