set rails_env for delayed_job

lib/capistrano/tasks/delayed_job.cap

@@ -3,20 +3,24 @@ namespace :delayed_job do
   task :start do
     on roles(:app) do
       within current_path do
+        with rails_env: fetch(:rails_env) do
           hostname = capture("hostname").strip
           execute :bundle, "exec", "script/delayed_job", "--queues=default,#{hostname}", "-n 2", "start"
         end
       end
     end
+  end
 
   desc "Stop delayed_job process"
   task :stop do
     on roles(:app) do
       within current_path do
+        with rails_env: fetch(:rails_env) do
           execute :bundle, "exec", "script/delayed_job", "stop"
         end
       end
     end
+  end
 
   desc "Restart delayed_job process"
   task :restart do