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