title: Invalidate Flask session?
body: <p>I'm testing JSON based login/logout functionality with httpie (<a href="https://github.com/jkbrzt/httpie#sessions" rel="nofollow">https://github.com/jkbrzt/httpie#sessions</a>).
  The problem I have is that once I login no matter how many times I "logout" I can not clean up the session.
  On the logout I can see clearly that the session is cleared, but when I call "status" afterwards the session 
  content is preserved (still there) ???</p>
  
  <p>Any idea what I'm doing wrong ? How to invalidate the Session on logout ?</p>
  
  <p>here is the code :</p>
  
  <pre><code>http  -v --session=log3 -j :5000/start/status
  http  -v --session=log3 -j :5000/start/logout
  http  -v --session=log3 -j :5000/start/status
  
  
  
  @start.route('/logout', methods=['GET'])
  def logout():
      print session
      session.pop('logged_in', None)
      session.clear()
      print session
      return jsonify({'rv' : 'ok' })
  
  @start.route('/status', methods=['GET'])
  def status():
    print session
    if 'logged_in' in session and session['logged_in'] :       
       return jsonify({'status' : True })
    return jsonify({'status' : False})
  </code></pre>