title: Can't run locust in debug mode
body: <p>Recently I switched from old locust version (0.14.2) to 1.3.1. Previously I was able to run in debug mode with command WebsiteUser().run() and it stops on all breakpoints.</p>
  <p>When I try to run new version with the same command I get next error:</p>
  <p>File &quot;/home/user/PycharmProjects/my_test/venv/lib/python3.7/site-packages/locust/user/users.py&quot;, line 210, in <strong>init</strong>
  super().<strong>init</strong>(*args, **kwargs)
  TypeError: <strong>init</strong>() missing 1 required positional argument: 'environment'</p>
  <p>I am sure that it's possible to debug new version as previous one, but what I am doing wrong?</p>
  <h3>Environment</h3>
  <ul>
  <li>OS: Ubuntu 18.04</li>
  <li>Python version: 3.7.4</li>
  <li>Locust version: 1.3.1</li>
  <li>Locust command line that you ran: WebsiteUser().run()</li>
  <li>Locust file contents:</li>
  </ul>
  <p><strong>locustfile.py:</strong></p>
  <pre><code>class UserBehaviour(MyTask):
  
      @task
      def task_one(self):
          self.action_one()
  
  
  class WebsiteUser(HttpUser):
      conf = Config()
      host = conf.host
      tasks = [UserBehaviour]
      wait_time = between(0.5, 1.5)
  
  if __name__ == &quot;__main__&quot;:
      WebsiteUser().run()
  </code></pre>
  <p><strong>my_task.py:</strong></p>
  <pre><code>class MyTask(BaseTaskSet):
  
      def action_one(self):
          self.client.get('dummy_path')
  </code></pre>