<ul>
  {% for item in include.collection %}
    <li>
    {% if item.url %}
      <a href="{{ item.url }}">{{ item.title }}</a>
    {% else %}
      {{ item.title }}
    {% endif %}
    </li>

    {% if item.post_list == true %}
      {% include post_list.html %}
    {% endif %}

    {% if item.entries != blank %}        
      {% include menu_item.html collection=item.entries %}
    {% endif %}
  {% endfor %}
</ul>
<ul>
  {% for item in include.collection %}
    <li>
    {% if item.url %}
      <a href="{{ item.url }}">{{ item.title }}</a>
    {% else %}
      {{ item.title }}
    {% endif %}
    </li>

    {% if item.post_list == true %}
      {% include post_list.html %}
    {% endif %}

    {% if item.entries %}
      {% include menu_item.html collection=item.entries %}
    {% endif %}
  {% endfor %}
</ul>
Fix menu item condition to avoid empty ul
Fix menu item condition to avoid empty ul

The values of the `entries` field in `_data/menu.yml` are either a list or `false`, however it was
compared to `blank` in `_include/menu_item.html`.  As a result, some empty `<ul></ul>`s were
generated in `_site/index.html`.
