MedNIST tutorial NotADirectoryError

[lyshc]

Describe the bug

NotADirectoryError: [Errno 20] Not a directory: './MedNIST/README.md'
The error is in this tutorial: https://github.com/Project-MONAI/MONAI/blob/master/examples/notebooks/mednist_tutorial.ipynb

To Reproduce

Steps to reproduce the behavior:

1. Go to the mednist_tutorial.ipynb and run code blocks 1-4. Error is for this line in block 4:

imageFiles = [[os.path.join(dataDir, classNames[i], x) for x in os.listdir(os.path.join(dataDir, classNames[i]))]
              for i in range(numClass)]

Environment (please complete the following information):

• OS: Linux version 4.19.104+ (using Google Colab)
• Python version: 3.6.9
• MONAI version [e.g. git commit hash]: 0.1.0

Additional context

Managed to fix error with replacing classNames variable also in block 4 with the following:
classNames = sorted([x for x in os.listdir(data_dir) if os.path.isdir(os.path.join(data_dir, x))])

[Nic-Ma]

Hi @lyshc ,

Thanks very much for your bug report!
This issue was caused by an update on the dataset file in the storage server.
And I already fixed in PR #301
Thanks.