Re: [PATCH 3/3] commit: give correct advice for empty commit during a rebase

"Johannes Schindelin via GitGitGadget" [off-list ref]
writes:

Note: we take pains to handle the situation when a user runs a `git
cherry-pick` _during_ a rebase. This is quite valid (e.g. in an `exec`
line in an interactive rebase). On the other hand, it is not possible to
run a rebase during a cherry-pick, meaning: if both `rebase-merge/` and
`sequencer/` exist, we still want to advise to use `git cherry-pick
--skip`.

Good description of why the code does what it does, that future
readers will surely appreciate.  Nice.