def run_exception_handlers(exception)
      status = true
      exception_handlers.each do |handler|
        status &&= begin
          handler.call(exception)
        rescue
          nil
        end
      end
      Isimud.retry_failures.nil? ? status : Isimud.retry_failures
    end
def run_exception_handlers(exception)
      status = true
      exception_handlers.each do |handler|
        status &&= begin
          handler.call(exception)
        rescue
          nil
        end
      end
      Isimud.retry_failures.nil? ? status : Isimud.retry_failures
    end
Call each of the exception handlers declared by #on_exception.
 @param [Exception] exception
 @return [Boolean] true if message should be requeued, false otherwise