git commit --amend --allow-empty
git push origin master
the git said that
! [rejected] master -> master (non-fast-forward) error: failed to push some refs to 'remoteurl' To prevent you from losing history, non-fast-forward updates were rejected Merge the remote changes (e.g. 'git pull') before pushing again. See the 'Note about fast-forwards' section of 'git push --help' for details.
Why? How to fix this?