Commit-queue should automatically handle PRs with merge commits from the target branch

Some contributors merge into their PR branch from main rather than rebasing. We might not recommend this, but it shouldn't be a major issue. Unfortunately it seems that the commit-queue label can't handle this, and fails with:

error: commit ... is a merge but no -m option was given.
fatal: cherry-pick failed

Here's a example I just ran into: https://github.com/nodejs/node/pull/59375#issuecomment-3178324429. More examples here.

AFAICT this then always requires manually landing the PR, but it feels like we should be able to handle these automatically without much trouble.

まず、cherry-pick を呼び出す commit queue の処理を特定し、その後、main からの merge を含む pull request で報告された失敗を再現します。完了とは、そのような pull request を手動で landing する必要なく commit queue が自動的に処理することです。この issue には、対象となるファイルや実行するテストの指定はありません。