title: MySQL CONVERT_TZ() returns null when one of the arguments is "+14:00"
body: <p>I am trying to convert UTC time into the users local time, it works fine until I try to convert the time to +14:00 timezone, the result is always null, anyone has idea?
  Here is my code:</p>
  
  <pre><code>select CONVERT_TZ(now(), '+00:00', '+14:00')
  </code></pre>