Revert D26744062: Add assert_async
Test Plan: revert-hammer
Differential Revision:
D26744062 (https://github.com/pytorch/pytorch/commit/12d63cc2f59e31c6472742babb6122eb1a1d7140)
Original commit changeset: be6d2653afe5
fbshipit-source-id: 972eaafcdf14d96abdec3dea6bcbd5cac1f3d759
