title: Why gzip is not consistent?
body: <p>Why these lines won't give me identical results?</p>
  
  <pre><code>&gt;&gt;&gt; gzip.compress('same'.encode('ascii'))
  b'\x1f\x8b\x08\x00\xe2\x0e0V\x02\xff+N\xccM\x05\x00D\xf1P\xfc\x04\x00\x00\x00'
  &gt;&gt;&gt; gzip.compress('same'.encode('ascii'))
  b'\x1f\x8b\x08\x00\xe3\x0e0V\x02\xff+N\xccM\x05\x00D\xf1P\xfc\x04\x00\x00\x00'
  </code></pre>
  
  <p>This is quite annoying for unit testing.</p>