还有一些git的指令没有用过，记录在这里．
１． 设置远程branch的指令
There is no tracking information for the current branch.
Please specify which branch you want to merge with.
See git-pull(1) for details.
git pull <remote> <branch>
If you wish to set tracking information for this branch you can do so with:
git branch --set-upstream-to=<remote>/<branch> configdrive-1