pytorch

255a3242 - add nesting_level as attribute to pickle for map datapipe (#61534)

add nesting_level as attribute to pickle for map datapipe (#61534) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/61534 currently, attribute `nesting_level` on `MapIterDataPipe` is not pickled. this yields `AttributeError` exceptions when multiprocessing with `DataLoader` this diff adds it as an attribute to pickle Test Plan: confirmed errors go away after change Reviewed By: ejguan Differential Revision: D29648655 fbshipit-source-id: 943b57eaff9712eb7ce92f43cb360acdb3111f2b