Very often I’m in the middle of an interactive rebase and while editing a
commit I remember I should have changed a commit that I initially didn’t mark
on the rebase todo. If you tried to git-rebase again you would notice it’s
not possible due to git’s bookkeeping of the current rebase.
In the past what I usually did was to either 1) Continue the rebase and then
rebase again to fix the previous commit or 2) Create a fixup commit with
git commit --fixup and then rebase again with --auto-squash.