modified the last line in download_and_convert_data.py scripts

slim/download_and_convert_data.py

@@ -67,7 +67,7 @@ def main(_):
     download_and_convert_mnist.run(FLAGS.dataset_dir)
   else:
     raise ValueError(
-        'dataset_name [%s] was not recognized.' % FLAGS.dataset_dir)
+        'dataset_name [%s] was not recognized.' % FLAGS.dataset_name)
 
 if __name__ == '__main__':
   tf.app.run()