title: Text cut off when using When layout renderer combined with a colon
body: <p>In a File target, I'm using a <strong><a href="https://github.com/NLog/NLog/wiki/When-Layout-Renderer" rel="nofollow">When</a></strong> layout renderer like this (simplified example):</p>
  
  <pre><code>layout="${when:when=1 == 1:inner=Test: Hello}"
  </code></pre>
  
  <p>I would expect the result to be <strong>Test: Hello</strong>. However, only <strong>Hello</strong> is logged, without <strong>Test:</strong>.</p>
  
  <p>I've already figured out that it has something to do with the colon, and I've tried solving the issue using several methods:</p>
  
  <ul>
  <li>Escaping it with \</li>
  <li>Wrapping it in a <a href="https://github.com/NLog/NLog/wiki/Literal-Layout-Renderer" rel="nofollow">Literal</a> layout renderer</li>
  <li>Replacing it with its ASCII code &amp;#58;</li>
  <li>Putting it in a separate variable</li>
  </ul>
  
  <p>But none of them seem to work.</p>
  
  <p>Is this a bug? Or am I doing something wrong?</p>