Emacs as git editor, what is Rebase mode?

When I run git rebase -i I get the absolutely horrible Rebase mode in emacs.

This only accepts some pre defined commads like

c -> Pick

r -> Reword

etc...

Even if I change to text mode emacs auto-magically makes the git-rebase-todo file read-only. How can I disable it?

The only solution I have found is to use vim as editor (something I don't want, I like emacs in general)