EM-mysql2 dead fiber from Rails exception patch

gistfile1.rb

module Mysql2
  module Fibered
    class Client < ::Mysql2::Client
      def query(sql, opts={})
        if ::EM.reactor_running?
          super(sql, opts.merge(:async => true))
          deferrable = ::EM::DefaultDeferrable.new
          ::EM.watch(self.socket, Watcher, self, deferrable).notify_readable = true
          fiber = Fiber.current
          deferrable.callback do |result|
            # Make sure fiber is still alive
            fiber.resume(result) if fiber.alive?
          end
          deferrable.errback do |err|
            # Make sure fiber is still alive
            fiber.resume(err) if fiber.alive?
          end
          Fiber.yield.tap do |result|
            raise result if result.is_a?(Exception)
          end
        else
          super(sql, opts)
        end
      end
    end
  end
end