readonly-plain-text with button addon

Created by: caiquecastro

The readonly plain text doesnt work with button addon.

Live example: https://codepen.io/caiquecastro/pen/eMdmYo

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
  <input type="text" readonly class="form-control-plaintext" id="staticEmail" value="email@example.com">
</div>