Evenly distribute output grad into all matching inputs for min/max/median (#43519)
Summary:
cc: ngimel mruberry
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43519
Reviewed By: albanD
Differential Revision: D23312235
Pulled By: ngimel
fbshipit-source-id: 678bda54996df7f29acf96add928bb7042fc2069
