使用git mrege-base命令可以查看，两个分支的最近的共同祖先：
$ git merge-base master origin/openwrt-21.02
46b6ee7ffc457af8aad1a0f7e5936f50041141d8
参考
https://stackoverflow.com/questions/1549146/git-find-the-most-recent-common-ancestor-of-two-branches