avoid killing JRuby's Fiber thread
avoid killing JRuby's Fiber thread

olleolleolle/celluloid,TiagoCardoso1983/celluloid,jasonm23/celluloid,seuros/celluloid,davydovanton/celluloid,marshall-lee/celluloid,dilumn/celluloid,kenichi/celluloid,celluloid/celluloid