disable downloading data in mnist.py (aws#805)

Author: chuyang-deng

sagemaker-python-sdk/pytorch_mnist/mnist.py

@@ -43,7 +43,7 @@ def _get_train_data_loader(batch_size, training_dir, is_distributed, **kwargs):
  dataset = datasets.MNIST(training_dir, train=True, transform=transforms.Compose([
  transforms.ToTensor(),
  transforms.Normalize((0.1307,), (0.3081,))
- ]), download=True)
+ ]))
  train_sampler = torch.utils.data.distributed.DistributedSampler(dataset) if is_distributed else None
  return torch.utils.data.DataLoader(dataset, batch_size=batch_size, shuffle=train_sampler is None,
  sampler=train_sampler, **kwargs)
@@ -55,7 +55,7 @@ def _get_test_data_loader(test_batch_size, training_dir, **kwargs):
  datasets.MNIST(training_dir, train=False, transform=transforms.Compose([
  transforms.ToTensor(),
  transforms.Normalize((0.1307,), (0.3081,))
- ]), download=True),
+ ])),
  batch_size=test_batch_size, shuffle=True, **kwargs)