git branch

git建分支的时候，可以指定源自哪个版本 默认是从当前的HEAD

git branch test

可以从某次提交 git branch test 2571682

从某个分支的HEAD git branch test dev

   <start-point>
       The new branch head will point to this commit. It may be given as a branch name, a commit-id, or a tag. If this option is omitted, the current HEAD will be used
       instead.