Ensure base path always starts and ends with /

The base path is an absolute path, so it should always start with /.
Whenever it is used, it must also always be followed by at least one /,
so baking that into the value makes sense. Finally, we can now
deduplicate the / in case the base path is the root.

templates/queue_table.html

@@ -12,7 +12,7 @@
         {% for task in tasks %}
         <tr {% if task.odd %} class="odd" {% endif %}>
             <td>
-                <a href="{{ base.root }}/commit/{{ task.hash }}">
+                <a href="{{ base.root }}commit/{{ task.hash }}">
                     {% call util::commit_short(task.short, task.reachable) %}
                 </a>
             </td>