title: Error! blahfile is not UTF-8 encoded. Saving disabled
body: <p>So, I'm trying to write a gzip file, actually from the net, but to simplify I wrote some very basic test.</p>
  
  <pre><code>import gzip
  LINES = [b'I am a test line' for _ in range(100_000)]
  f = gzip.open('./test.text.gz', 'wb')
  for line in LINES:
      f.write(line)
  f.close()
  </code></pre>
  
  <p>It runs great, and I can see in Jupyter that it has created the test.txt.gz file in the directory listing.  So I click on it expecting a whole host of garbage characters indicative of a binary file, like you would see in Notepad.<br>
  However, instead I get this ...</p>
  
  <pre><code>Error!  test.text.gz is not UTF-8 encoded.
  Saving disabled.
  See console for more details
  </code></pre>
  
  <p>Which makes me think, oh my god, coding error, something is wrong with my encoding, my saving, can I save bytes ?  Am I using the correct routines ??  And then spend 5 hours trying all combinations of code and modules.</p>