hint: Updates were rejected because the remote contains work that you dohint: not have locally. This is usually caused by another repository pushing

# git push -u origin master
Username for 'http://gitlab.com': test
Password for 'http://test@gitlab.com':
To http://gitlab.com/root/test.git
! [rejected] master -> master (fetch first)
error: failed to push some refs to 'http://gitlab.com/root/test.git'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first merge the remote changes (e.g.,
hint: 'git pull') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.

 

라고 에러뜨면서 push 가 안되면

# git push -f origin master 하면 정상적으로 올라간다.