Mina: Sin caché para el agrupador

Estoy usando este script (se actualizó desde mina 0.3)

require 'mina/bundler'
require 'mina/rails'
require 'mina/git'
require 'mina/rbenv'

set :shared_dirs, %w(log public/uploads node_modules)
set :current_path, 'current'
set :term_mode, nil

task :environment do
  invoke :'rbenv:load'
end

task setup: :environment do
  command %[mkdir -p "#{fetch(:shared_path)}/log"]
  command %[chmod g+rx,u+rwx "#{fetch(:shared_path)}/log"]

  command %[mkdir -p "#{fetch(:shared_path)}/public/uploads"]
  command %[chmod g+rx,u+rwx "#{fetch(:shared_path)}/public/uploads"]
  command %[mkdir -p "#{fetch(:shared_path)}/node_modules"]
  command %[chmod g+rx,u+rwx "#{fetch(:shared_path)}/node_modules"]
end

desc 'Deploys the current version to the server.'
task deploy: :environment do
  deploy do
    invoke :'git:clone'
    invoke :'deploy:link_shared_paths'
    invoke :'bundle:install'
    invoke :'rails:db_migrate'
    invoke :'npm_install'
    invoke :'rails:assets_precompile'
    invoke :'deploy:cleanup'

    on :launch do
      command "mkdir -p #{fetch(:current_path)}/tmp/"
      command "touch #{fetch(:current_path)}/tmp/restart.txt"
    end
  end
end

task :restart do
  command "touch #{fetch(:current_path)}/tmp/restart.txt"
end

task :logs do
  command 'echo "Contents of the log file are as follows:"'
  command "tail -f #{fetch(:current_path)}/log/#{fetch(:rails_env)}.log"
end

task :npm_install do
  command 'npm install --production'
end

El problema es que bundle install está descargando todas las gemas desde cero cada vez que se realiza la implementación. Funcionaba bien en la versión 0.3.

¿Alguna idea de qué estoy haciendo mal?