git branch {tagname}-branch {tagname}
git checkout {tagname}-branch
`git add .`
`git ci -m "Fix included" `
or cherry-pick the commit, whatever is easier
`git cherry-pick {num_commit}`
`git tag -d {tagname}`
`git tag {tagname}`
`git push origin :{tagname} // deletes original remote tag`
`git push origin {tagname} // creates new remote tag`
This is based on https://gist.github.com/739288 thanks to nickfloyd for it