Rake without RAILS_ENV variable gives 'DEVELOPMENT' while RAILS_ENV_PRODUCTION results in TRUE

Question

To explain this issue I wrote the following rake task

namespace :tutorial do
 desc 'tutorial'
 task :env =>:environment do
  puts "RAILS_ENV: #{RAILS_ENV}"
  puts "RAILS_ENV_PRODUCTION: #{RAILS_ENV_PRODUCTION}" 
  puts "RAILS_ENV_TEST: #{RAILS_ENV_TEST}" 
 end
end

When I run the following commands:

rake tutorial:env

it will return

RAILS_ENV: development
RAILS_ENV_PRODUCTION: true
RAILS_ENV_TEST: false

I find it strange that RAILS_ENV_PRODUCTION is true, while RAILS_ENV is DEVELOPMENT (I assume development is the preferred default value for most Rake tasks.)

The following commands give expected results

rake tutorial:env RAILS_ENV=development

RAILS_ENV: development
RAILS_ENV_PRODUCTION: false
RAILS_ENV_TEST: false



rake tutorial:env RAILS_ENV=production

RAILS_ENV: production
RAILS_ENV_PRODUCTION: true
RAILS_ENV_TEST: false

Can someone please explain the strange result of the first rake command without the RAILS_ENV being set.

I use Ruby 1.8.7 Rails 2.1.0 OS: Mac OS X 10.6.4

Thanks.