BUG: `git commit` adding unstaged chunks of files to commits on 2.33.0

Hello all,

As described in the subject line, it seems like git commit is
committing entire files when chunks of the files are staged using `git
add -p`, in spite of leaving chunks out of the stage. See below for
the bug-report template questionnaire. Please let me know if there is
anything I can do to help resolve this issue or if there is anything
needed.

Thanks,

Andrew Thorp

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

Edit a checked-in file, adding multiple chunks of lines to the file.
Using `git add -p <file>`, stage one of the chunks, leave some chunks unstaged.
After running `git status` the file should both in the section
`Changes to be committed:` and `Changes not staged for commit`.
Commit the changes.

What did you expect to happen? (Expected behavior)

I expected all staged changes to be committed and unstaged changes to
remain unstaged.

What happened instead? (Actual behavior)

The entire file was committed, including the unstaged chunks of changes.

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

It appears as though the remaining file lines were both checked in and
committed, when only the later should have happened.

[System Info]
git version:
git version 2.33.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Darwin 20.4.0 Darwin Kernel Version 20.4.0: Thu Apr 22 21:46:47
PDT 2021; root:xnu-7195.101.2~1/RELEASE_X86_64 x86_64
compiler info: clang: 12.0.5 (clang-1205.0.22.9)
libc info: no libc information available
$SHELL (typically, interactive shell): /bin/zsh