JIT Testing: Improve assertAutodiffNode error message (#50626)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50626
Test Plan: Imported from OSS
Reviewed By: mruberry
Differential Revision: D25932184
Pulled By: Lilyjjo
fbshipit-source-id: 6fa5a652eb1a0c10bb9d9040b9a708fdf93aaf46
