commit: --amend -m '' silently fails to wipe message
`git commit --amend -m ''` seems to be an unambiguous request to blank a
commit message, but it actually leaves the commit message as-is. That's
the case regardless of whether `--allow-empty-message` is specified, and
doesn't so much as drop a non-zero return code.
Add failing tests to show this behaviour.
Signed-off-by: Adam Dinwoodie <adam@dinwoodie.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
projects / thirdparty / git.git / commit
