Pushed something unwanted to a public git repository by accident.
Well, if you are lucky, you notice it very early. In 10 seconds, usually :)
Damage is done, let's try to undo it - fast.
Solution #11) Remove the incriminated commit from the local repo:
git rebase -i
2) Forced push to the remote repo:
git push -f origin +branchname
Solution #2(works for undoing the last N commit only)
git push -f origin HEAD^:branchname
What's left? Crossing fingers and hope noone has pulled the repo during your manoeuvres :)