title: moment.js will not parse UK format date even when setting the locale
body: <p>Quite simply, this is my code:</p>
  
  <p><a href="http://jsfiddle.net/NibblyPig/k9zb4ysp/" rel="nofollow noreferrer">http://jsfiddle.net/NibblyPig/k9zb4ysp/</a></p>
  
  <pre><code>moment.locale('en-GB');
  
  var d = moment('22/12/2019');
  
  alert(d);
  </code></pre>
  
  <p>I would expect this to parse, however it says invalid date.</p>
  
  <p>I have referenced <code>moment.js</code> and the <code>locale/en-gb.js</code></p>
  
  <p>I'm writing a global control so the date may come in in a variety of formats.</p>
  
  <p>If I put in a variety of American dates they all work, for example <code>12/12/2019</code>, <code>12/12/2019 23:04</code> etc.</p>
  
  <p>However the locale command does not appear to do anything and I cannot get a single date to parse. What am I doing wrong?</p>