Keep on getting `invalid changes in the merge commit`

In github.com/lemonade-sdk/lemonade we use squash merging and also use a merge queue. In experimenting with stacks we keep running into this situation:

Pretty much we queue up the entire stack, one layer merges and the rest are pulled. So then we have to monitor the next layer, requeue all of them etc.

The entire stack that showed this problem is here:
https://github.com/lemonade-sdk/lemonade/pull/3584

You can see the earlier layers how many times they got pulled out of the merge queue because of "invalid changes in the merge commit".

首先重現連結的 lemonade pull request 中所描述的堆疊 PR 情境，並檢查 gh-stack 如何與 GitHub 的 merge queue 互動。完成條件是：佇列中的 stack 在其中一層合併後可以繼續推進，而後續層不會因為 "invalid changes in the merge commit" 而被反覆移除。

由索引模型根據 Issue 內容生成。