問題：

 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'https://github.com/NULLcaption/project.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Integrate the remote changes (e.g.
hint: 'git pull ...'
 
) before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

核心問題：

Updates were rejected because the tip of your current branch is behind its remote counterpart. Integrate the remote changes (e.g.’git pull …’) before pushing again.

其實質就是原生代碼和遠端程式碼倉庫的專案不一致，解決這個問題，有以下幾種辦法：
1.使用強制push的方法：

$ git push -u origin master -f

這樣會使遠端修改丟失，一般是不可取的，尤其是多人協作開發的時候。

2.push前先將遠端repository修改pull下來

$ git pull origin master

$ git push -u origin master

3.若不想merge遠端和本地修改，可以先建立新的分支：

$ git branch [name]

然後push

$ git push -u origin [name]