问题描述：
Updates were rejected because the tip of your current branch is behind
情景：
在github或coding上创建项目，然后本地git init
然后没有git pull -f --all
导致github上的版本里有readme文件和本地版本冲突，下面给出冲突原因：
[master][~/Downloads/ios] git push -u origin master
Username for 'https://github.com': shiren1118
Password for 'https://shiren1118@github.com':
To https://github.com/shiren1118/iOS_code_agile.git
! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to 'https://github.com/shiren1118/iOS_code_agile.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Merge the remote changes (e.g. 'git pull')
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
查看大部分资料，只有这个有用
http://www.cnblogs.com/xwdreamer/archive/2012/05/29/2523958.html
勾选强制覆盖已有的分支（可能会丢失改动），再点击上传，上传成功。
只有这句是核心，所以，本人就略微想了一下
[master][~/Downloads/ios] git push -u origin master -f
原文地址：https://blog.csdn.net/shiren1118/article/details/7761203