Capistrano 3 with Git Submodules

git.cap

# Save this file as lib/capistrano/tasks/git.cap

namespace :git do
  desc 'Copy repo to releases'
  task create_release: :'git:update' do
    on roles(:all) do
      with fetch(:git_environmental_variables) do
        within repo_path do
          execute :git, :clone, '-b', fetch(:branch), '--recursive', '.', release_path
        end
      end
    end
  end
end

Thank you. After deployed I found I 'cd' to the directory of submodule and found that 'git branch' point to no branch. So I have to add another task to force it checkout to master branch. Any ideas?

 desc 'Checkout master'
  task :checkout_master do
      on roles(:app) do |host|
          within current_path do
              execute "cd #{app_path}/current/public/pages && git checkout master && cd ../../"
          end
      end
  end

I got NameError: uninitialized constant Capistrano::Git in Capistrano 3.6.0