The purpose here is to check that the task is never acknowledged since it has a 0 timeout. See [executeIfCallbackNotExpired](https://github.com/wajam/bwl/blob/1b40edf90baebc1c6ee6323778105b260622e023/bwl-core/src/main/scala/com/wajam/bwl/Bwl.scala#L152).