Collapse panel sizing

[futuremint]

From @janxious:
Ran into an issue with some code that was in the following shape:

<ul class="list-group">
  <li class="list-group-item list-group-custom-thing-form" id="some-list-group-item">
    <input type="text" class="form-control" placeholder="thing name" name="thing-name" pattern="[A-Za-z0-9]+" required="required">
    <button type="button" class="btn btn-default btn-create"><i class="fuelux-icon fuelux-icon-plus-sign"></i>Add</button>
  </li>
  <li class="list-group-item">
    <a data-toggle="collapse" a href="#collapseExampleLink" aria-expanded="false" aria-controls="collapseExample">Watch collapse in action</a>
    <a data-toggle="collapse" aria-expanded="false" aria-controls="some-list-group-item" href="#some-list-group-item" class="btn btn-link"><i class="fuelux-icon fuelux-icon-plus-sign"></i>Add A Thing</a>
  </li>
</ul>

The un-collapse worked correctly, but the re-collapse left a partial height visible list-group-item. It seemed like it was the height of the padding/margin above the text input.