title: Python requests .post hangs on large HTTPS payload
body: <p>I am uploading some data to a graph DB using a POST call, as follows:</p>
  
  <pre><code>            with open(turtle, 'rb') as data:
                  if graph:
                      params = {graph_param: f"&lt;{graph}&gt;"}
                  post(
                      url=f"{self.repo}/statements",
                      data=data,
                      verify=False,
                      auth=HTTPBasicAuth(self.username, self.password),
                      params=params,
                      headers={
                          'Content-Type': 'application/x-turtle',
                          'Content-Encoding': 'gzip'
                      })
  </code></pre>
  
  <p>When the endpoint is HTTPS and the payload is large (over 5MB or so), the upload succeeds (I see the data show up in the DB), but the post request never returns, the script hangs. If I access via the HTTP gateway or upload smaller files (tested with as large as 2.7MB), it works fine.</p>
  
  <p>This is using Python 3.7 running within Git Bash on a Windows 10 machine.</p>