HOWTO: Change the message of a pushed commit

• git rebase -i
• In you editor now change pick to reword on the line for the incorrect commit.
• Once you have done, save and close.
• Now the editor opens again with the message to correct. Do your correction, save and close
• git push --force

This method will rewrite the history of your repository. If someone pulled/fetched from the repo between the commit with the wrong message and when you correct it, he/she could have some issues. It would be useful to communicate to anyone involved about your action.