title: Moment.js bug while adding 1 week at last week of year
body: <p>I am trying to add one week whatever user has selected week and year and i need output in 'week year' format.</p>
  
  <p>I tried to use momentjs. check below example, instead of giving '1 2016' its giving '1 2015'.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var test = moment('52 2015','w YYYY').add(1,'w').format('w YYYY');
  $('body').html(test);</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"&gt;&lt;/script&gt;
  &lt;script src='http://momentjs.com/downloads/moment.min.js'&gt;&lt;/script&gt;</code></pre>
  </div>
  </div>
  </p>