git diff ^! syntax stopped working for stashes in Git 2.28

[Tim Jaacks <tim.jaacks@garz-fricke.com>]

Hello,

I noticed that the following syntax to show the changes of a stash stopped working in Git 2.28:

  git diff stash@{0}^!

It still works on commits and HEAD, though:

  git diff f27984d^!
  git diff HEAD^!

And diffing against the stash's parent works as well:

  git diff stash@{0}^1 stash@{0}

I assume this is a bug. Can anybody confirm this? I verified the behavior change trying different Git versions via docker:

  docker run -it --rm --user $(id -u):$(id -g) -v $HOME:$HOME:rw -v /etc/passwd:/etc/passwd:ro -v /etc/group:/etc/group:ro -v $PWD:$PWD:rw -w $PWD bitnami/git:2.27.0 diff stash@{0}^!

With v2.27.0 the above syntax works, with v2.28.0 and later it doesn't.

Kind regards,
Tim

-- 
Tim Jaacks
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