protect edge future against ConcurrencyError form JRuby
protect edge future against ConcurrencyError form JRuby

hobodave/concurrent-ruby,hobodave/concurrent-ruby,lucasallan/concurrent-ruby,lucasallan/concurrent-ruby,hobodave/concurrent-ruby,lucasallan/concurrent-ruby,lucasallan/concurrent-ruby,hobodave/concurrent-ruby,lucasallan/concurrent-ruby