Bundler doesn't load gem in production rails app - ruby-on-rails

Question

I'm having a problem where a single gem is not being loaded by bundler in a rails app, but only in production - there's no problem using the gem in development mode.
The gem is country_select, and we've tried it with version 1.1.3 and the github repository. The app is using rails 3.2.11.
Proof that the gem exists on the server
The gem is successfully installed by bundler in the production environment:
$ RAILS_ENV=production bundle install
...
Using coffee-rails (3.2.2)
Using country_select (1.1.3)
Using daemons (1.1.9)
...
Your bundle is complete! It was installed into /home/deploy/rails-app/shared/bundle
The gem appears in the shared gem directory that bundler installs to:
$ ls -al /home/deploy/rails-app/shared/bundle/ruby/1.9.1/gems/ | grep country
drwxrwxr-x 3 deploy deploy 4096 Apr 3 08:49 country_select-1.1.3
And the gem is loaded when starting rails from the console:
$ RAILS_ENV=production script/rails c
Loading production environment (Rails 3.2.11)
irb(main):002:0> Gem.loaded_specs.keys.grep /country/
=> ["country_select"]
However...
That same check for the country_select gem in the rails app fails. For example:
class ApplicationController < ActionController::Base
before_filter do
raise Gem.loaded_specs.keys.grep(/country/).inspect
end
#...
end
Spits out [] - i.e. the gem is not loaded. Plus, parts of the application that rely on the gem fail as a result of it not existing.
And finally, the question
Simply adding a require 'country_select' somewhere in the startup means that the gem gets loaded, and the app works. But why isn't bundler doing it with that particular gem, despite the fact that it installs it and adds it to the app's gem directory?
More info about the production environment:
$ rvm -v
rvm 1.18.18 (stable)...
$ ruby -v
ruby 1.9.3p392 (2013-02-22 revision 39386) [x86_64-linux]
$ gem -v
1.8.25
$ bundle -v
Bundler version 1.3.2
Update: 5th April 2013
The problem seems to have "gone away". After a couple of redeployments, it appears to be working. This is in spite of the fact that the country_select gem hasn't been changed, which is very odd. I'm still looking into exactly what has changed in that time, but I'm puzzled.

Answer 1

try running
RAILS_ENV=production bundle exec script/rails c

Answer 2

I have an app using the same versions and I don't need to require the gem in dev or production. I also tried with your before_filter and got ["country_select"] as expected. So the problem isn't with the gem.
I think you're either monkeying around with the loaded gems in initialization somewhere (unlikely) or there's something going wrong with your setup around the server. Are you starting the server with RAILS_ENV=production bundle exec script/rails server? Can you check the gem path being used by the server includes the shared gem path you mentioned in your question?