title: Output and Broadcast shape mismatch in MNIST, torchvision
body: <p>I am getting following error when using MNIST dataset in Torchvision</p>
  
  <pre><code>RuntimeError: output with shape [1, 28, 28] doesn't match the broadcast shape [3, 28, 28]
  </code></pre>
  
  <p>Here is my code:</p>
  
  <pre><code>import torch
  from torchvision import datasets, transforms
  
  transform = transforms.Compose([transforms.ToTensor(),
                              transforms.Normalize((0.5, 0.5, 0.5), (0.5, 0.5, 0.5)),
                            ])
  trainset = datasets.MNIST('~/.pytorch/MNIST_data/', download=True, train=True, transform=transform)
  trainloader = torch.utils.data.DataLoader(trainset, batch_size=64, shuffle=True)
  images, labels = next(iter(trainloader))
  </code></pre>