title: Who changed the response._content_consumed to True when debuging testing case of python requests
body: <p>When I read the source code of the <a href="https://github.com/requests/requests" rel="nofollow noreferrer">requests</a> I try to debug the testing case for tracing code with vscode and python extension.
  When I run the <code>test_digestauth_401_count_reset_on_redirect</code> function in <em>test_lowlevel.py</em>, I encounter a weird question.After getting the first response of four from the internal Server thread,the registered hook function <code>handle_401</code> is called and if I set a breakpoint at the line of <code>r.content</code> in <code>handle_401</code> I found that the 'r._content_consumer' is <strong>True</strong>.But before the <code>r.content</code>, the result of executing <code>print(r._content_consumed)</code> is <strong>False</strong>. I don't know why and who set the <code>r._content_consumed</code> to True.</p>
  
  <p>And then I debug the same code with pdb, everything is OK. both <code>print(r._content_consumed)</code> and <code>pdb p r._content_consumed</code> are False.</p>
  
  <p>Environment:
  OS Version: Win10 64bit</p>
  
  <p>Python Version:3.6.1</p>
  
  <p>VSCode Version:1.9.1 ia32</p>
  
  <p>Python extension:0.9.1</p>
  
  <p><a href="https://i.stack.imgur.com/EujVi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/EujVi.png" alt="print statement and breakpoint"></a>
  <a href="https://i.stack.imgur.com/oF4uV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oF4uV.png" alt="debug val content and print result"></a></p>