Add missing endblock directives.

sphinx/templates/layout.html

@@ -150,7 +150,7 @@
 {%- block bottomrelbar %}
 {{ relbar }}
 {%- endblock %}
-{%- block beforefooter %}
+{%- block beforefooter %}{% endblock %}
 {%- block footer %}
     <div class="footer">
     {%- if hasdoc('copyright') %}
@@ -163,6 +163,6 @@
     {%- endif %}
     </div>
 {%- endblock %}
-{%- block afterfooter %}
+{%- block afterfooter %}{% endblock %}
   </body>
 </html>