test_allreduce_coalesced_stress message passed in as kwarg (#25557)
Summary:
addresses https://github.com/pytorch/pytorch/issues/25427, see issue discussion for more context.
message conversion to unicode is a potential source of flakiness, passing in as kwarg instead of to `prec` is both more clear and resilient to being broken in the future.
cc mrshenli
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25557
Differential Revision: D17160343
Pulled By: pietern
fbshipit-source-id: af071fecc04c7e0a6658694dc0d76472193f8e78
