Bundler ignoring install of MySQL2 gem when run on my 'production' server

Question

I'm attempting to install the 'mysql2' gem on my production server using Capistrano.

I want to use SQLite in development, and MySQL in production.

I develop on a Windows 7 machine, and production is using Ubuntu.

When I run bundle install on my development machine, it installs MySQL2.

When Capistrano runs it against my production machine, it doesn't even get a mention in the output.

When I run the same command on my production machine directly on the shell, it too doesn't mention the gem.

I'm also finding that gem 'therubyracer', :platforms => :ruby isn't being installed. I added this after the mysql2 entry. I'm hoping the two are related. mysql2 wasn't working before I added therubyracer.

As a result of all of the above, I'm getting the following error when I'm attempting to view my site:

Please install the mysql2 adapter: gem install activerecord-mysql2-adapter (mysql2 is not part of the bundle. Add it to Gemfile.)

Additional Info

I hope the amount of info I'm including below is more useful than it is a pain.

gemfile

I appreciate I could place mysql2 in 'production' but that didn't work.

source 'http://rubygems.org'

gem 'rails', '3.1.1'
gem 'nokogiri'
gem 'bcrypt-ruby'
gem 'faker'
gem 'will_paginate'
gem 'capistrano'
gem 'capistrano-ext'
gem 'mysql2', "~> 0.3"
gem 'therubyracer', :platforms => :ruby
gem 'sqlite3'

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '~> 3.1.4'
  gem 'coffee-rails', '~> 3.1.1'
  gem 'uglifier', '>= 1.0.3'
end

gem 'jquery-rails'

group :test do
  # Pretty printed test output
  gem 'turn', :require => false
end

Output of Capistrano Bundle Install command

  * executing "cd /home/gannicott.co.uk/production/listen/www/releases/20120223225131 && bundle install --gemfile /home/gannicott.co.uk/prod
uction/listen/www/releases/20120223225131/Gemfile --path /home/gannicott.co.uk/production/listen/www/shared/bundle --deployment --without de
velopment test"
    servers: ["homer.gannicott.co.uk"]
    [homer.gannicott.co.uk] executing command
    [homer.gannicott.co.uk] sh -c 'cd /home/gannicott.co.uk/production/listen/www/releases/20120223225131 && bundle install --gemfile /home/
gannicott.co.uk/production/listen/www/releases/20120223225131/Gemfile --path /home/gannicott.co.uk/production/listen/www/shared/bundle --dep
loyment --without development test'
 ** [out :: homer.gannicott.co.uk] Installing rake (0.9.2.2)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing multi_json (1.1.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing activesupport (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing builder (3.0.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing i18n (0.6.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing activemodel (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing erubis (2.7.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rack (1.3.6)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rack-cache (1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rack-mount (0.8.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rack-test (0.6.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing hike (1.2.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing tilt (1.3.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing sprockets (2.0.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing actionpack (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing mime-types (1.17.2)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing polyglot (0.3.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing treetop (1.4.10)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing mail (2.3.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing actionmailer (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing arel (2.2.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing tzinfo (0.3.31)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing activerecord (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing activeresource (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing highline (1.6.11)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing net-ssh (2.3.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing net-scp (1.0.4)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing net-sftp (2.0.5)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing net-ssh-gateway (1.1.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing capistrano (2.11.2)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing capistrano-ext (1.2.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing coffee-script-source (1.2.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing execjs (1.3.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing coffee-script (2.2.0)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rack-ssl (1.3.2)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing json (1.6.5)
 ** [out :: homer.gannicott.co.uk] with native extensions
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rdoc (3.12)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing thor (0.14.6)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing railties (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing coffee-rails (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing faker (1.0.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing jquery-rails (1.0.19)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Using bundler (1.0.21)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing rails (3.1.1)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing sass (3.1.15)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing sass-rails (3.1.5)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing uglifier (1.2.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Installing will_paginate (3.0.3)
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Updating .gem files in vendor/cache
 ** [out :: homer.gannicott.co.uk]
 ** [out :: homer.gannicott.co.uk] Your bundle is complete! It was installed into /home/gannicott.co.uk/production/listen/www/shared/bundle
 ** [out :: homer.gannicott.co.uk]
    command finished in 12924ms

capistrano's deploy.rb

require 'bundler/capistrano'
require 'capistrano/ext/multistage'
# Based on: http://guides.beanstalkapp.com/deployments/deploy-with-capistrano.html
set :application, "listen_later"

set :scm, :git
set :repository, "repos location"
set :scm_passphrase, "passphrase"

set :user, "username"

set :stages, ["staging", "production"]
set :default_stage, "staging"

# The following needs to be added to avoid a failure (http://discuss.joyent.com/viewtopic.php?id=27326)
default_run_options[:pty] = true

namespace :deploy do
  desc "Tell Passenger to restart the app."
  task :restart do
    run "touch #{current_path}/tmp/restart.txt"
  end
end

# Removed --silent so I can see what's going on
set :bundle_flags,    "--deployment"

capistrano's production deploy file

server "homer.gannicott.co.uk", :app, :web, :db, :primary => true
set :deploy_to, "/home/gannicott.co.uk/production/listen/www"

Database config file

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
development:
  adapter: sqlite3
  database: db/development.sqlite3
  pool: 5
  timeout: 5000

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  adapter: sqlite3
  database: db/test.sqlite3
  pool: 5
  timeout: 5000

production:
  adapter: mysql2
  encoding: utf8
  reconnect: false
  database: databasename
  pool: 5
  username: username
  password: password
  #socket: **/opt/local/var/run/mysql5/mysqld.sock**

#  adapter: sqlite3
#  database: db/production.sqlite3
#  pool: 5
#  timeout: 5000

Cheers!