queue_close.rb - fix 'warning: instance variable @closed not initialized' on Ruby 2.2
queue_close.rb - fix 'warning: instance variable @closed not initialized' on Ruby 2.2

eileencodes/puma,eileencodes/puma,eileencodes/puma,puma/puma,eileencodes/puma,puma/puma,puma/puma,puma/puma