How to fix "corrupted" interactive rebase?

I got stuck in this. I created the head-name file, and then I ran into another error saying it couldn't find the onto file, so I created that file. Then I got another error saying could not read '.git/rebase-apply/onto': No such file or directory.

So I looked at the git documentation for rebasing and found another command:

git rebase --quit

This set me back on my branch with no changes, and I could start my rebase over again, good as new.

It looks like Git tried to remove the .git/rebase-merge directory but wasn't able to remove it completely. Have you tried copying that folder away? Also copy away the .git/rebase-apply folder if that is present.