Asset rake tasks not available on Rails 3.1 app in production

When I run "bund开发者_JS百科le exec rake -T" in development, the assets:clear and assets:precompile tasks show up, but if I prefix that command with RAILS_ENV=production, or run it on a server where that variable is set, they don't. Has anyone run into this?

I'd removed rails/all from the application.rb and replaced it with the individual railties, excluding activerecord. Turns out you also need to require the sprockets railtie.