Skip asset compilation in Capistrano 3 if no assets have changed since last deploy

skip_asset_compilation.cap

namespace :deploy do
  Rake::Task["deploy:compile_assets"].clear_actions
  task :compile_assets => [:set_rails_env] do
    run_locally do
      if capture("git --no-pager diff #{fetch(:previous_revision)} #{fetch(:current_revision)} app/assets vendor/assets").empty?
         info "Skipping assets compilation"
      else
        invoke 'deploy:assets:precompile'
        invoke 'deploy:assets:backup_manifest'
      end
    end
  end
end