Connection Error when using wmt19_translate/zh-en dataset

Short description
Encounter connection error when downloading wmt19_translate/zh-en dataset.

Environment information

• Operating System: Colab
• Python version: Python 3.6.7
• tf-nightly-gpu-2.0-preview version: 2.0.0-dev20190514

Reproduction instructions

!pip install tf-nightly-gpu-2.0-preview
import tensorflow_datasets as tfds
import tensorflow as tf

examples, metadata = tfds.load("wmt19_translate/zh-en", 
                               with_info=True, 
                               as_supervised=True,
                               data_dir="wmt"
                              )

Link to logs

Downloading and preparing dataset wmt19_translate (2.04 GiB) to wmt/wmt19_translate/zh-en/0.0.2...
Dl Completed...
4/|/ 40% 4/10 [01:33<00:59, 9.97s/ url]
Dl Size...
1404/|/100% 1404/1404 [01:33<00:00, 46.68 MiB/s]
Extraction completed...
4/|/100% 4/4 [01:33<00:00, 27.15s/ file]

---------------------------------------------------------------------------
TimeoutError                              Traceback (most recent call last)
/usr/lib/python3.6/urllib/request.py in ftp_open(self, req)
   1533         try:
-> 1534             fw = self.connect_ftp(user, passwd, host, port, dirs, req.timeout)
   1535             type = file and 'I' or 'D'

42 frames
TimeoutError: [Errno 110] Connection timed out

During handling of the above exception, another exception occurred:

URLError                                  Traceback (most recent call last)
/usr/lib/python3.6/socket.py in create_connection(address, timeout, source_address)
    711             if source_address:
    712                 sock.bind(source_address)
--> 713             sock.connect(sa)
    714             # Break explicitly a reference cycle
    715             err = None

URLError: <urlopen error ftp error: TimeoutError(110, 'Connection timed out')>

Expected behavior
Complete downloading dataset without error.

Start by running the provided Colab reproduction with tfds.load("wmt19_translate/zh-en") and review the reported FTP timeout after extraction. Trace the dataset download path to determine whether the failure is reproducible and identify a verified way for the dataset to complete downloading without the connection error.