Reverting a remote repo is a bit tricky in the sense of it already being published. ;\
I did 'merge' your commit into my repo using the 'Fork Queue', but it doesn't really give the desired result. I would rather see commits merged in instead of recommitted. I did a merge into branch alr2 just for comparison.
Now that I have a reference to your tag we can see what happens if we don't play nice. ]:)
Now it's a 'pick your poison' game.
If you don't care about keeping a reference to that commit, just do
$ git reset HEAD^
do fiddling and commit again.
The push will result in a failure, so you'll need to remove the remote reference.
See http://github.com/guides/remove-a-remote-branch