Re: amend warnings with no changes staged

[Jonathan Nieder <jrnieder@gmail.com>]

Lukas Gross wrote:

> I had intended to stage commits but forgot to do so. Git responded
> with a normal commit creation message, so I pushed to the remote to
> begin a CI build. When the build failed for the same reason, I
> realized I had forgotten to stage the changes. An additional line in
> the response to the effect of “Warning: did you mean to amend with no
> changes?” would be very helpful to shorten this feedback loop.

On second thought:

	$ git commit --amend --no-edit
	[detached HEAD 33a3db8805] Git 2.23-rc1
	 Author: Junio C Hamano <gitster@pobox.com>
	 Date: Fri Aug 2 13:12:24 2019 -0700
	 2 files changed, 2 insertions(+), 1 deletion(-)
	$

Some non-judgemental descriptive output like

	$ git commit --amend --no-edit
	No changes.
	$

would address this case, without bothering people who are doing it
intentionally.  So I think there's room for a simple improvement here.

Care to take a stab at it?  builtin/commit.c would be the place to
start.

Thanks and sorry for the roller-coaster,
Jonathan