title: Bootstrap 3, Less: issue with changing placeholder color with & operator and multiple pseudo elements on the same line
body: <p>I'm trying to style the placeholder, and I noticed that placing multiple nested pseudo elements on the same line like this doesn't seem to work:</p>
  
  <pre><code>.form-group {
      .form-control{
          &amp;::-webkit-input-placeholder, &amp;:-moz-placeholder, &amp;::-moz-placeholder, &amp;:-ms-input-placeholder{
              color: @brand-primary;
          }
      }
  }
  </code></pre>
  
  <p>Yet placing them separately like this does:</p>
  
  <pre><code>.form-group {
      .form-control{
          &amp;::-webkit-input-placeholder{
              color: @brand-primary;
          }
          &amp;::-moz-placeholder{
              color: @brand-primary;
          }
          &amp;::-moz-placeholder{
              color: @brand-primary;
          }
          &amp;:-ms-input-placeholder{
              color: @brand-primary;
          }
      }
  }
  </code></pre>
  
  <p>I'm still learning Less, and I was under the impression that the first example was the right way to do things, so I was wondering what is going on here, and if I'm doing something wrong, can anyone point it out?</p>