Message are not delivered to some nodes in the network

Here are the logs [link](https://drive.google.com/file/d/1uNH-A3MEWQddJgnprCVhhwLFgk0_FkOf/view?usp=sharing).

The 2283242'th block is generated at 2019-07-30 10:37:49+09:00.
The 2283241'th block is generated at 2019-07-30 10:37:25+09:00.

The "m-eu-central-1-3" node couldn't collect all the precommits of 2283241'th block. So the node generated 2283242'th block too late. This caused view changes.

首先檢查區塊 2283241 和 2283242 附近的相關日誌，重點關注 m-eu-central-1-3 以及缺失的 precommits。追蹤訊息傳遞和檢視變更的處理位置，然後驗證所有必要的 precommits 都會在產生下一個區塊之前到達，並且該故障不再導致檢視變更。

由索引模型根據 Issue 內容生成。