Notes

Sometimes I make a commit accidentally or make a mistake; miss a file, add a file I shouldn't, leave a debug (print statement), etc.

I need to fix the mistake, and pretend it never happened in the first place. So I need to revert the last commit.

I do it with:

git reset HEAD~
.
// do your stuff
git add <your files>
git commit -c ORIG_HEAD

The git commit -c ORIG_HEAD command will open the editor with previous commit message. Edit away.

Apparently, using -C argument means you don't need to change the commit message.