Since 4.0.0 'nil' values are ignored inside cycle tag

The code below has different renders using liquid versions <=3.0.6 and 4.0.0

{% for i in (1..4) %}
  {% cycle '<section>', nil %}
    <div>
      <p>{{ i }}</p>
    </div>
  {% cycle nil, '</section>' %}
{% endfor %}

3.0.6 Two 'section' blocks:

  <section>
    <div>
      <p>1</p>
    </div>

    <div>
      <p>2</p>
    </div>
  </section>

  <section>
    <div>
      <p>3</p>
    </div>

    <div>
      <p>4</p>
    </div>
  </section>

4.0.0 Four 'section' blocks:

  <section>
    <div>
      <p>1</p>
    </div>
  </section>

  <section>
    <div>
      <p>2</p>
    </div>
  </section>

  <section>
    <div>
      <p>3</p>
    </div>
  </section>

  <section>
    <div>
      <p>4</p>
    </div>
  </section>

The upgrade to 4.0.0 is breaking the appearance of a website I'm supporting. I've not found any documentation references for such 'cycle' usage, so I'm not sure if it is some hack worked in previous verions or it's a bug of 4.0.0.

Start by reproducing the supplied cycle-tag example under Liquid 3.0.6 and 4.0.0, then trace the cycle tag entry point and its handling of nil values. Done means the intended grouping is established and covered by a regression test, with the example rendering consistently under the supported behavior.