bug report - `git diff --quiet --cached` returns 0 when a rename is staged

Thank you for filling out a Git bug report! Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)

  $ mkdir /tmp/git-diff-test; cd /tmp/git-diff-test
  $ git init 
  Initialized empty Git repository in /tmp/git-diff-test/.git/
  $ touch foo 
  $ git add foo 
  $ git commit -m "foo"
  [main (root-commit) f60d7bc] foo
   1 file changed, 0 insertions(+), 0 deletions(-)
   create mode 100644 foo
  $ mv foo bar 
  $ git status -s
   D foo
  ?? bar
  $ git add foo bar 
  $ git status -s
  R  foo -> bar
  $ git diff --quiet --cached; echo $?
  0
  $ git diff --quiet --cached --no-renames; echo $?
  1

What did you expect to happen? (Expected behavior)

  Versions prior to commit d7b97b7185521e3b9364b3abc6553df2480da173
  returned 1 for `git diff --quiet --cached`.

What happened instead? (Actual behavior)

  It returned 0.

What's different between what you expected and what actually happened?

  The status code.

Anything else you want to add:

  This bug report originates from a PR I filed with Magit here:

  https://github.com/magit/magit/pull/5221

  I thought this difference between using `--no-renames` and not made
  sense, so I thought the problem lied with Magit. However, like tarsius in
  that thread points out, this is a change that happened recently with git
  and it's not in the release notes. After finding the commit that
  introduces the change, I see the message mentions "The new options are
  off by default, keeping the old behavior." It really doesn't seem
  intentional, so here's a bug report.

  Also, the above difference with --no-renames also happens if I move my
  ~/.gitconfig elsewhere, so there's no use of external diff tools. I
  verified that with strace, too.

Please review the rest of the bug report below. You can delete any lines you don't wish to share.

[System Info]
git version:
git version 2.46.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
libcurl: 8.9.0
OpenSSL: OpenSSL 3.3.1 4 Jun 2024
zlib: 1.3.1
uname: Linux 6.10.6-arch1-1 #1 SMP PREEMPT_DYNAMIC Mon, 19 Aug 2024 17:02:39 +0000 x86_64
compiler info: gnuc: 14.1
libc info: glibc: 2.40
$SHELL (typically, interactive shell): /usr/bin/zsh

[Enabled Hooks]