远程分支已经删除，对应的本地分支还存在
# git remote show origin
* remote origin
Fetch URL: git@github.com:xxx/xxx.git
Push URL: git@github.com:xxx/xxx.git
HEAD branch: master
Remote branches:
master tracked
refs/remotes/origin/b1 stale (use 'git remote prune' to remove)
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)
# git remote prune origin
删除本地过时分支