title: Missing Host header in HTTP requests from the requests Python library
body: <p>Where is the <a href="https://www.rfc-editor.org/rfc/rfc7230#section-5.4" rel="nofollow noreferrer">HTTP/1.1 mandatory Host header field</a> in HTTP request messages generated by the <code>requests</code> Python library?</p>
  <pre><code>import requests
  
  response = requests.get(&quot;https://www.google.com/&quot;)
  print(response.request.headers)
  </code></pre>
  <p>Output:</p>
  <blockquote>
  <p>{'User-Agent': 'python-requests/2.22.0', 'Accept-Encoding': 'gzip, deflate', 'Accept': '*/*', 'Connection': 'keep-alive'}</p>
  </blockquote>