Rails cron with whenever, setting the environment

This question will probably only make sense if you know about the whenever gem for creating cron jobs. I have a task in my schedule.rb like

every 1.day, :at => '4am' do
  command "cd #{RAILS_ROOT} && rake thinking_sphinx:stop RAILS_ENV=#{RAILS_ENV}"
  command "cd #{RAILS_ROOT} && rake thinking_sphinx:index RAILS_ENV=#{RAILS_ENV}"
  command "cd #{RAILS_ROOT} && rake thinking_sphinx:start RAILS_ENV=#{RAILS_ENV}"
end

However when I update my crontab using

whenever --update-crontab appname --set environment=production

the cron jobs still have RAILS_ENV=development. My tasks on production and development are the same right now, I just need to change the environment variable because thinking_sphinx needs to know the current environment. Any ideas on how to do this?

Thanks!