jekyll/docs/_includes/tutorials_ul.html

<ul>
{% for item in include.items %}
  {% assign item_url = item | prepend:"/tutorials/" | append:"/" %}
  {% assign p = site.tutorials | where:"url", item_url | first %}
  <li {%- if item_url == page.url %} class="current" {%- endif %}><a href="{{ p.url }}">{{ p.title }}</a></li>
{% endfor %}
</ul>