Как заставить Rails исключить некоторые связанные гемы из загрузки плагинов?

I have a Rails application that uses Bundler for dependency management. I've got the following in my Gemfile:

# default group:
gem 'json'

group 'development' do
  gem 'my_profiler'
end

group 'test' do
  gem 'mocha'
end

group 'deployment' do
  gem 'foo'
end

I call Bundler.setup(:default, RAILS_ENV.to_sym) and Bundler.require(:default, RAILS_ENV.to_sym) in my initializers.

The problem is that since Bundler puts the gems into vendor/bundle/, Rails initializes all gems that have an init.rb, not just those for the current environment. How do I prevent Rails from automatically loading Foo's init.rb?