It was also a bit pointless to checkout a new branch just to switch back. The whole thing should be

    git branch some-new-branch-name
    git reset --hard origin/master
    git checkout some-new-branch-name

The "committed to wrong branch" case is also a little overly complex. I'd just do:

    git checkout correct-branch
    git cherry-pick wrong-branch
    git checkout wrong-branch
    git reset --hard HEAD~

This is less safe than the branching alternatives. Instead of "moving" the original commit, this copies the original commit to a new one and leaves the original one dangling and waiting to be garbage collected.

Also, if you have more than one commit before you noticed you were on the wrong branch, this only grabs the one commit.

tip: you can use @{u} to refer to "the upstream of my current branch", ie. what you said but will work no matter what the remote is called.

the website's example is for when you only want to undo just the last commit you made.