don't double-apply the renderer logic

since that leads to double-finishing requests too

src/allmydata/web/common.py

@@ -526,6 +526,10 @@ def render_exception(render):
             method=request.method,
             handler=fullyQualifiedName(bound_render),
         )
+        if getattr(request, "dont_apply_extra_processing", False):
+            with action:
+                return bound_render(request)
+
         with action.context():
             result = DeferredContext(maybeDeferred(bound_render, request))
             result.addBoth(_finish, bound_render, request)

src/allmydata/web/directory.py

@@ -400,7 +400,10 @@ class DirectoryNodeHandler(ReplaceMeMixin, Resource, object):
         # delegate to it. We could return the resource back out of
         # DirectoryNodeHandler.renderHTTP, and nevow would recurse into it,
         # but the addCallback() that handles when_done= would break.
-        d.addCallback(lambda child: child.render(req))
+        def render_child(child):
+            req.dont_apply_extra_processing = True
+            return child.render(req)
+        d.addCallback(render_child)
         return d
 
     def _POST_uri(self, req):