Code suggested in Documentation does not work

[jaanisfehling]

In the docs it says:

By default this calls defaultLoginHandler, which concatenates plugin widgets and wraps the result in authLayout. Override if you need fancy widget containers, additional functionality, or an entirely custom page. For example, in some applications you may want to prevent the login page being displayed for a user who is already logged in, even if the URL is visited explicitly; this can be done by overriding loginHandler in your instance declaration with something like:

instance YesodAuth App where
...
loginHandler = do
ma <- lift maybeAuthId
when (isJust ma) $
lift $ redirect HomeR -- or any other Handler code you want
defaultLoginHandler

But this does not work for me. Instead I found this to work:

loginHandler :: AuthHandler App Html
loginHandler = do
    ma <- maybeAuthId
    when (isJust ma) $ redirect HomeR
    defaultLoginHandler