Dont redefine RAILS_ENV once set

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2425 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/lib/initializer.rb

 require 'logger'
 
-old_verbose, $VERBOSE = $VERBOSE, nil
-RAILS_ENV = ENV['RAILS_ENV'] || 'development'
-$VERBOSE = old_verbose
+RAILS_ENV = ENV['RAILS_ENV'] || 'development' unless defined?(RAILS_ENV)
 
 module Rails
   # The Initializer is responsible for processing the Rails configuration, such as setting the $LOAD_PATH, requiring the