title: Is session.modified = True in flask redundant now?
body: <p>As Flask API documentation says, I need to add </p>
  
  <pre><code>session.modified = True
  </code></pre>
  
  <p>after my code in order to propagate session changes to mutable structures like dict/list.</p>
  
  <p>As I understand, session object won't see any changes and won't add modified session data to cookies. </p>
  
  <p>Example#1 from docs:</p>
  
  <pre><code>session['objects'].append(42)
  # so mark it as modified yourself
  session.modified = True
  </code></pre>
  
  <p>Example#2 from google:</p>
  
  <pre><code># Add a logout handler.
  @app.route('/logout')
  def logout():
      # Delete the user's profile and the credentials stored by oauth2.
      del session['profile']
      session.modified = True
      oauth2.storage.delete()
      return redirect(request.referrer or '/')
  </code></pre>
  
  <p>But I tried Flask 1.0.2 and Flask 0.10.1. Everything <strong>also</strong> works without <code>session.modified = True</code> between requests. I see changes, cookies are updated.</p>
  
  <p>Is that line redundant now?</p>