Fix EMNSIT download URL (#1318)

* fix url

* update comment

Author: Philip Meier

torchvision/datasets/mnist.py

@@ -226,8 +226,11 @@ class EMNIST(MNIST):
         target_transform (callable, optional): A function/transform that takes in the
             target and transforms it.
     """
-    # Updated URL from https://www.westernsydney.edu.au/bens/home/reproducible_research/emnist
-    url = 'https://cloudstor.aarnet.edu.au/plus/s/ZNmuFiuQTqZlu9W/download'
+    # Updated URL from https://www.nist.gov/node/1298471/emnist-dataset since the
+    # _official_ download link
+    # https://cloudstor.aarnet.edu.au/plus/s/ZNmuFiuQTqZlu9W/download
+    # is (currently) unavailable
+    url = 'http://www.itl.nist.gov/iaui/vip/cs_links/EMNIST/gzip.zip'
     splits = ('byclass', 'bymerge', 'balanced', 'letters', 'digits', 'mnist')
 
     def __init__(self, root, split, **kwargs):