When restarting thin via Capistrano changes aren't picked up

Question

In my deploy.rb I have the following tasks:

namespace :deploy do
    task :start, :roles => :app do
        run "cd #{current_path} && bundle exec thin start -C config/thin.yml"
    end

    task :stop, :roles => :app do
        run "cd #{current_path} && bundle exec thin stop -C config/thin.yml"
    end

    task :restart, :roles => :app do
        run "cd #{current_path} && bundle exec thin restart -C config/thin.yml"
    end 
end

When I run cap deploy:restart via cap deploy recent code changes are not picked up. However, if I subsequently run cap deploy:stop and cap cap deploy:start all changes are picked up.

Why doesn't thin recognize the new current directory?