GitLab

* fixed padding size of input tensor for reduce scatter, and fixed an error that assigned wrong group

* Update fairscale/nn/data_parallel/fully_sharded_data_parallel.py
Co-authored-by: Min Xu <24926999+min-xu-ai@users.noreply.github.com>

* added changelog

* fixed some commit.

* added unit test to ensure the reduce_scatter process group size is correct in default cases. And fall back to default process grouop when the reduce_scatter process group has the wrong size.

* throw an error instead of rolling back to use default process group for reduce_scatter_process_group

* Revert "throw an error instead of rolling back to use default process group for reduce_scatter_process_group"

This reverts commit eab5620da3b726ea55d3088ae4ca10d94dcdf4d9.

* added check for None to avoid unit test failure

* fixed an error to avoid the unit tests failure
Co-authored-by: Min Xu <24926999+min-xu-ai@users.noreply.github.com>