Warbler should respect RAILS_ENV variable and when it is defined, it should use it as the environment for the web.xml.
If the variable is not defined, warbler should fall back to "production" environment.

Patch for my config/warble.rb:

diff --git a/foo/config/warble.rb b/foo/config/warble.rb
--- a/foo/config/warble.rb
+++ b/foo/config/warble.rb
@@ -55,7 +55,7 @@ Warbler::Config.new do |config|
   # config.war_name = "mywar"
 
   # Value of RAILS_ENV for the webapp
-  config.webxml.rails.env = 'production'
+  config.webxml.rails.env = ENV['RAILS_ENV'] || 'production'
 
   # Application booter to use, one of :rack, :rails, or :merb. (Default :rails)
   # config.webxml.booter = :rails