title: Django errors about HTTP_HOST from domain an extra dot after it
body: <p>I'm all over the <code>ALLOWED_HOSTS</code> setting in Django. It has been set on all my production sites for a while now but one site in particular has been throwing out weird debug emails. The site works fine (for me) but about once a week I'll get an email along the lines of:</p>
  
  <pre><code> SuspiciousOperation: Invalid HTTP_HOST header 
    (you may need to set ALLOWED_HOSTS): thepcspy.com.
  
  
  &lt;WSGIRequest
  path:/,
  GET:&lt;QueryDict: {}&gt;,
  POST:&lt;QueryDict: {}&gt;,
  COOKIES:{},
  META:{...
   'HTTP_HOST': 'thepcspy.com.',
   'SERVER_NAME': 'thepcspy.com',
  ...
  </code></pre>
  
  <p>Notice the full stop after the domain in the error and in <code>HTTP_HOST</code>. As far as I can see in my nginx config, there isn't anything that could add an extra dot after the name on <code>HTTP_HOST</code> (note that <code>SERVER_NAME</code> is correct). What on earth is going on here?</p>
  
  <p>Should I just write this off as somebody intentionally trying to break my server?</p>