Repository: pytorch
Issue: AttributeError: module 'torch.distributed' has no attribute 'init_process_group' on torch 1.3 aarch64
Labels: oncall: distributed,triaged

## 🐛 Bug

I get the error: 

> AttributeError: module 'torch.distributed' has no attribute 'init_process_group'

when running the following code (see reproduce). I am using the Jetson Nano and have installed torch through the [PyTorchv1.3.0 pip wheel for linux aarch64 using Python 3.6](https://devtalk.nvidia.com/default/topic/1049071/pytorch-for-jetson-nano-version-1-3-0-now-available/). 

## To Reproduce

Steps to reproduce the behavior:

Run the following code:

```
"""run.py:"""
#!/usr/bin/env python
import os
import torch
import torch.distributed as dist
from torch.multiprocessing import Process

def run(rank, size):
    """ Distributed function to be implemented later. """
    pass

def init_process(rank, size, fn, backend='gloo'):
    """ Initialize the distributed environment. """
    os.environ['MASTER_ADDR'] = '127.0.0.1'
    os.environ['MASTER_PORT'] = '29500'
    dist.init_process_group(backend, rank=rank, world_size=size)
    fn(rank, size)


if __name__ == "__main__":
    size = 2
    processes = []
    for rank in range(size):
        p = Process(target=init_process, args=(rank, size, run))
        p.start()
        processes.append(p)

    for p in processes:
        p.join()
```

Which is [just some tutorial code.](https://pytorch.org/tutorials/intermediate/dist_tuto.html)

Output:

```
Process Process-1:
Process Process-2:
Traceback (most recent call last):
  File "/usr/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "run.py", line 16, in init_process
    dist.init_process_group(backend, rank=rank, world_size=size)
AttributeError: module 'torch.distributed' has no attribute 'init_process_group'
Traceback (most recent call last):
  File "/usr/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "run.py", line 16, in init_process
    dist.init_process_group(backend, rank=rank, world_size=size)
AttributeError: module 'torch.distributed' has no attribute 'init_process_group'
```

<!-- If you have a code sample, error messages, stack traces, please provide it here as well -->

## Environment

Output:
```
PyTorch version: 1.3.0
Is debug build: No
CUDA used to build PyTorch: 10.0.326

OS: Ubuntu 18.04.2 LTS
GCC version: (Ubuntu/Linaro 7.4.0-1ubuntu1~18.04.1) 7.4.0
CMake version: Could not collect

Python version: 3.6
Is CUDA available: Yes
CUDA runtime version: Could not collect
GPU models and configuration: Could not collect
Nvidia driver version: Could not collect
cuDNN version: /usr/lib/aarch64-linux-gnu/libcudnn.so.7.3.1

Versions of relevant libraries:
[pip3] numpy==1.17.4
[pip3] torch==1.3.0
[pip3] torchvision==0.5.0a0+2d7c066
[conda] Could not collect
```


cc @pietern @mrshenli @pritamdamania87 @zhaojuanmao @satgera @rohan-varma @gqchen @aazzolini @xush6528