message: support passing in a source url to the mnist read_data_sets function, to make it easier to use 'fashion mnist' etc.
diff: @@ -30,7 +30,7 @@ from tensorflow.python.framework import random_seed
  from tensorflow.python.platform import gfile
  # CVDF mirror of http://yann.lecun.com/exdb/mnist/
  -SOURCE_URL = 'https://storage.googleapis.com/cvdf-datasets/mnist/'
  +DEFAULT_SOURCE_URL = 'https://storage.googleapis.com/cvdf-datasets/mnist/'
  def _read32(bytestream):
  @@ -215,7 +215,8 @@ def read_data_sets(train_dir,
  dtype=dtypes.float32,
  reshape=True,
  validation_size=5000,
  - seed=None):
  + seed=None,
  + source_url=DEFAULT_SOURCE_URL):
  if fake_data:
  def fake():
  @@ -227,28 +228,31 @@ def read_data_sets(train_dir,
  test = fake()
  return base.Datasets(train=train, validation=validation, test=test)
  + if not source_url: # empty string check
  + source_url = DEFAULT_SOURCE_URL
  +
  TRAIN_IMAGES = 'train-images-idx3-ubyte.gz'
  TRAIN_LABELS = 'train-labels-idx1-ubyte.gz'
  TEST_IMAGES = 't10k-images-idx3-ubyte.gz'
  TEST_LABELS = 't10k-labels-idx1-ubyte.gz'
  local_file = base.maybe_download(TRAIN_IMAGES, train_dir,
  - SOURCE_URL + TRAIN_IMAGES)
  + source_url + TRAIN_IMAGES)
  with gfile.Open(local_file, 'rb') as f:
  train_images = extract_images(f)
  local_file = base.maybe_download(TRAIN_LABELS, train_dir,
  - SOURCE_URL + TRAIN_LABELS)
  + source_url + TRAIN_LABELS)
  with gfile.Open(local_file, 'rb') as f:
  train_labels = extract_labels(f, one_hot=one_hot)
  local_file = base.maybe_download(TEST_IMAGES, train_dir,
  - SOURCE_URL + TEST_IMAGES)
  + source_url + TEST_IMAGES)
  with gfile.Open(local_file, 'rb') as f:
  test_images = extract_images(f)
  local_file = base.maybe_download(TEST_LABELS, train_dir,
  - SOURCE_URL + TEST_LABELS)
  + source_url + TEST_LABELS)
  with gfile.Open(local_file, 'rb') as f:
  test_labels = extract_labels(f, one_hot=one_hot)
  