Double bottom border: Card with .card-header + .list-group

Created by: hiddewie

When making a card and using a .card-header with a .list-group, a double border is present (bottom of the header and top of the list group). I think this is not intended.

As far as I've seen this has been a problem since BS 4 alpha-5.

HTML:

<div class="card">
  <h3 class="card-header">Test header</h3>
  <ul class="list-group list-group-flush">
    <li class="list-group-item justify-content-between">
      Some content
    </li>
    <li class="list-group-item justify-content-between">
      Some content
    </li>
  </ul>
</div>

Screenshot:

Details

Operating system: Windows 10 Browser: Chrome 55.0.2883.87 m (Also validated on Firefox 50.1.0 and Opera 42.0.2393.94) Test case: http://www.bootply.com/ZkNFalLacR