[Edit: It seems that I was mistaken but I'm leaving this up to illustrate the confusion. In my experience "second to last" isn't common and "next to last" is much more common, which I think is why I was confused because I thought they were different, but apparently they are the same. I wonder if there is a regional usage pattern to these phrases. ]

This seems like mistake or a non-standard usage of the english phrase "second to last". Given a git log of:

    $ git log --oneline
    15e0437 - (HEAD -> master) this is the third commit
    f82d1fd - this is the second commit
    9180c17 - initial commit

I would call "f82d1fd" the "next to last commit" and it can be referred to as HEAD~ I would call "9180c17" the "second to last commit" and it can be referred to as HEAD~2