config/environments/development.rb を config/environments/ci.rb にコピーしました。
RAILS_ENV=development で実行すると、アセット検索パスに、特に jquery-ui-rails の gem ベンダー ディレクトリが含まれます。ただし、RAILS_ENV=ci で実行すると、そうではありません。
コンソールから、 Rails.application.config.assets.paths は開発で次のように評価されます
irb(main):002:0> Rails.application.config.assets.paths
=> ["/var/www/ci/conflux/app/assets/images",
"/var/www/ci/conflux/app/assets/javascripts",
"/var/www/ci/conflux/app/assets/stylesheets",
"/var/www/ci/conflux/vendor/assets/stylesheets",
"/opt/comcast/ruby1.9.3/lib/ruby/gems/1.9.1/gems/jquery-rails-1.0.19/vendor/assets/javascripts",
"/opt/comcast/ruby1.9.3/lib/ruby/gems/1.9.1/gems/jquery-ui-rails-1.0.0/vendor/assets/images",
"/opt/comcast/ruby1.9.3/lib/ruby/gems/1.9.1/gems/jquery-ui-rails-1.0.0/vendor/assets/javascripts",
"/opt/comcast/ruby1.9.3/lib/ruby/gems/1.9.1/gems/jquery-ui-rails-1.0.0/vendor/assets/stylesheets"]
しかし、ciの場合、私は次のものしか得られません:
irb(main):002:0> Rails.application.config.assets.paths
=> ["/var/www/ci/conflux/app/assets/images",
"/var/www/ci/conflux/app/assets/javascripts",
"/var/www/ci/conflux/app/assets/stylesheets",
"/var/www/ci/conflux/vendor/assets/stylesheets",
"/opt/comcast/ruby1.9.3/lib/ruby/gems/1.9.1/gems/jquery-rails-1.0.19/vendor/assets/javascripts"]