<!DOCTYPE html>
<html>

  {% include head.html %}

  <body class="two-col dept">

    {% include header.html %}

    <div class="page-content">
      <div class="wrapper">
        {% unless  page.github == undefined %}
        <div class="github-links">
          <div class="button-group">
            <a class="button" href="https://github.com/{{ page.github }}">
              <img alt="octoface" src="{{site.baseurl}}/images/octoface.svg" height="20px" style="display:inline;vertical-align: middle;" />
              View on GitHub
            </a>
            <a class="button" href="https://github.com/{{ page.github }}/zipball/master">
              <img alt="zip" src="{{site.baseurl}}/images/file-zip.svg" height="20px" style="display:inline;vertical-align: middle;" />
              Download .zip
            </a>
            <a class="button" href="https://github.com/{{ page.github }}/tarball/master">
              <img alt="zip" src="{{site.baseurl}}/images/file-zip.svg" height="20px" style="display:inline;vertical-align: middle;" />
              Download .tar.gz
            </a>
          </div>
        </div>
        {% endunless %}
        <h1>{% if page.title %}{{ page.title }}{% else %}{{ site.title }}{% endif %}</h1>
        <hr />

        {{ content }}
      </div>
    </div>

    {% include footer.html %}

  </body>

</html>

<!DOCTYPE html>
<html>

  {% include head.html %}

  <body class="two-col dept">

    {% include header.html %}

    <div class="page-content">
      <div class="wrapper">
        {% unless  page.github == undefined %}
        <div class="github-links">
          <div class="button-group">
            <a class="button" href="https://github.com/{{ page.github }}">
              <img alt="octoface" src="{{site.baseurl}}/images/octoface.svg" height="20px" style="display:inline;vertical-align: middle;" />
              View on GitHub
            </a>
            {% if page.github contains '/' %}
            <a class="button" href="https://github.com/{{ page.github }}/zipball/master">
              <img alt="zip" src="{{site.baseurl}}/images/file-zip.svg" height="20px" style="display:inline;vertical-align: middle;" />
              Download .zip
            </a>
            <a class="button" href="https://github.com/{{ page.github }}/tarball/master">
              <img alt="zip" src="{{site.baseurl}}/images/file-zip.svg" height="20px" style="display:inline;vertical-align: middle;" />
              Download .tar.gz
            </a>
            {% endif %}
          </div>
        </div>
        {% endunless %}
        <h1>{% if page.title %}{{ page.title }}{% else %}{{ site.title }}{% endif %}</h1>
        <hr />

        {{ content }}
      </div>
    </div>

    {% include footer.html %}

  </body>

</html>

Make the GitHub buttons work sensibly when there is only an organisation specified, not a project.
Make the GitHub buttons work sensibly when there is only an organisation specified, not a project.