SPF not working with django, back arrow not changing page

Question

I'm using spfjs, refer to this link - http://youtube.github.io/spfjs/ but when I click the back arrow after clicking on the link with the .spf-link class and going to that page, it doesn't change the page, it only updates the title.

<script src="https://cdnjs.cloudflare.com/ajax/libs/spf/2.4.0/spf.js"></script>
<script>
  spf.init();
</script>

<li class="is-inline"><a href="{% url 'signup' %}" class="spf-link">Sign Up</a></li>