When doing a git rebase -i and, say, squashing two commits together, Git will bring up an editor with the commit messages in it for me to edit.

Normally when I do a stand-alone git commit, I use the -v option so that the message file I’m editing also includes, below the “cut” line, a diff of the commit against the previous commit.

How do I get this same commit -v behaviour when I’m doing an interactive rebase? (Note that I can’t just type git commit -v manually, since the commit process is started and run for me by git rebase -i.)