Fix for torch.save not saving source files (#28965)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28965
Fixed the reference to correct object
Test Plan:
Added new unit test test_serialization_save_warnings in test_torch
Verified by running the test_torch tests
Imported from OSS
Differential Revision: D18306797
fbshipit-source-id: bbdc7a1aa59a395fcbb736bcc7c3f96db45454d3
