title: 503 error logging in using Python MechanicalSoup
body: <p>I want to scrape some information behind a login page but I get a 503</p>
  
  <p>This is what happens when I try to login with mechanicalsoup (same result with robobrowser):</p>
  
  <pre><code>&gt;&gt;&gt; import mechanicalsoup
  &gt;&gt;&gt; browser = mechanicalsoup.StatefulBrowser(user_agent='Mozilla/5.0')
  &gt;&gt;&gt; page = browser.get('https://X.com')
  &gt;&gt;&gt; page.status_code
  200
  &gt;&gt;&gt; page = browser.get('https://X.com/wp-login.php')
  &gt;&gt;&gt; page.status_code
  503
  </code></pre>
  
  <p>I've tried a couple of different user_agents, how can I get around this? moving cookies around?</p>