title: Proper POST file upload (load testing with Locust)
body: <p>I'm trying to make a load test for Django-based website.</p>
  
  <p>I use Locust 0.7.3 and python 2.7.10</p>
  
  <p>Here I make POST - filling the form and attaching some file:</p>
  
  <pre><code>class WebsiteTasks(TaskSet):
      def on_start(self):
          self.client.get("/")
  
      @task
      def submit(self):
          response = self.client.get("/submit/")
          csrftoken = response.cookies['csrftoken']
          attach = open('file.pdf', 'rb')
  
          r = self.client.post("/submit/", {
             'csrfmiddlewaretoken': csrftoken,
             'password': smart_str(u'wkefjgui'),
             'payload': smart_str(u'kjsdgfljdsh'),
             'docfile': attach,
             'commit': smart_str(u'Вкрапить / Embed'),
          })
  </code></pre>
  
  <p>Everything's seemed to be ok, but on the server's upload folder there's no file!</p>
  
  <p>What I'm doing wrong?</p>