has-error does not change the color of buttons in an input-group

Created by: adelinor

Buttons in an input-group do not get their border colour changed when there is a parent element with has-error .

Example:

<div class="has-error" style="margin: 2em; width: 300px;">
<div class="input-group">
    <input type="text" class="form-control" value="zzz">
    <span class="input-group-btn">
        <button type="button" class="btn btn-default">Search</button>
    </span>
</div>
<p class="help-block">No results found for the provided criteria</p>
</div>

See the attached picture to see how it renders.

I would expect something more like the screen shot below.