Fix date check in machine history display

logs/templates/logs/machine_history.html

@@ -56,7 +56,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
                     {% endif %}
                 </td>
                 <td>
-                    {% if event.start_date %}
+                    {% if event.end_date %}
                         {{ event.end_date }}
                     {% else %}
                         {% trans "Now" %}