Avoid attribute indirection with `env` (#13212)

doc/development/tutorials/examples/todo.py

@@ -76,7 +76,7 @@ def process_todo_nodes(app, doctree, fromdocname):
 
     # Replace all todolist nodes with a list of the collected todos.
     # Augment each todo with a backlink to the original location.
-    env = app.builder.env
+    env = app.env
 
     if not hasattr(env, 'todo_all_todos'):
         env.todo_all_todos = []