title: $_SERVER['HTTP_USER_AGENT'] changing on Safari (iOS)
body: <p>I have noticed that Safari provides different user agents depending on what seems to be the state of the session in php. The very first connection to the server provides a user agent string like this:</p>
  
  <blockquote>
    <p>MobileSafari/9537.53 CFNetwork/672.1.13 Darwin/14.0.0</p>
  </blockquote>
  
  <p>But any later connections once the session is started gives:</p>
  
  <blockquote>
    <p>Mozilla/5.0 (iPad; CPU OS 7_1 like Mac OS X) AppleWebKit/537.51.2 (KHTML, like Gecko)_Version/7.0 Mobile/11D167 Safari/9537.53</p>
  </blockquote>
  
  <p><strong>What is going on?</strong> I am storing a hash of the the user agent in my session wrapper in an attempt to limit damage from a compromised account. Does this mean I will have to scrap that check?</p>
  
  <p>(I have only tested this on iOS7 and PHP)</p>