[BUG] setuptools 84.0.0 no longer preserves executable bit on  package_data  files in wheels

setuptools version

84.0.0

Python version

Python 3.12, 3.14

OS

RHEL8, Ubuntu 24.04

Additional environment information

No response

Description

Since setuptools 84.0.0, executable permission bits (e.g.  +x  on scripts included via  package_data ) are silently dropped from wheels. setuptools 83.0.0 preserves them correctly.

Expected behavior

Mode bits should not be changed from 83.0.0 to 84.0.0

How to Reproduce

mkdir pkg
cat << EOF > pkg/pyproject.toml
[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

[project]
name = "mypkg"
version = "0.0.1"

[tool.setuptools.package-data]
mypkg = ["scripts/*"]
EOF

mkdir -p pkg/mypkg/scripts
printf '#!/usr/bin/env python\nprint("hi")\n' > pkg/mypkg/scripts/some_script.py
chmod 755 pkg/mypkg/scripts/some_script.py
touch pkg/mypkg/__init__.py

python -m venv venv83 && venv83/bin/pip install setuptools==83.0.0 build
python -m venv venv84 && venv84/bin/pip install setuptools==84.0.0 build

cd pkg
../venv83/bin/python -m build --wheel --no-isolation -o ../dist83 .
../venv84/bin/python -m build --wheel --no-isolation -o ../dist84 .
cd ..

unzip -Z -l dist83/*.whl | grep some_script
unzip -Z -l dist84/*.whl | grep some_script

Output

$ unzip -Z -l dist83/*.whl | grep some_script
-rwxr-xr-x  2.0 unx       34 b-       36 defN 26-Aug-10 07:28 mypkg/scripts/some_script.py
$ unzip -Z -l dist84/*.whl | grep some_script
-rw-rw-r--  2.0 unx       34 b-       36 defN 26-Aug-10 07:28 mypkg/scripts/some_script.py

Start by running the supplied reproduction with setuptools 83.0.0 and 84.0.0, focusing on the package's pyproject.toml and mypkg/scripts/some_script.py. Trace the wheel-building path responsible for package_data permissions and add coverage for the executable-bit regression. Done means the generated wheel preserves the script's 755 mode as in 83.0.0.