Set PIP_CONFIG_FILE=/dev/null by default when invoking pip to build+install the wheel

User pip configuration (e.g. require-virtualenv = true in ~/.pip/pip.conf)
can interfere with the wheel build, causing unexpected failures.
Since %pyproject_wheel runs pip in the RPM build environment,
user-level pip settings are never appropriate.

However, if the packager sets PIP_CONFIG_FILE in spec,
it still takes precedence.

Assisted-By: Claude Opus 4.6
(cherry picked from Fedora commit 30df8fe217)

macros.pyproject

@@ -111,6 +111,7 @@ if [ -z "$specifier" ]; then
   echo 'ERROR: %%%%pyproject_install found no wheel in %%%%{_pyproject_wheeldir} %{_pyproject_wheeldir}' >&2
   exit 1
 fi
+PIP_CONFIG_FILE="${PIP_CONFIG_FILE:-/dev/null}" \
 TMPDIR="%{_pyproject_builddir}" %{__python3} -m pip install --root %{buildroot} --prefix %{_prefix} --no-deps --disable-pip-version-check --progress-bar off --verbose --ignore-installed --no-warn-script-location --no-index --no-cache-dir --find-links %{_pyproject_wheeldir} $specifier
 if [ -d %{buildroot}%{_bindir} ]; then
   %py3_shebang_fix %{buildroot}%{_bindir}/*

pyproject-rpm-macros.spec

@@ -207,6 +207,7 @@ export HOSTNAME="rpmbuild"  # to speedup tox in network-less mock, see rhbz#1856
 - getopt: Fix global macro clobbering with save/restore stack
 - %%pyproject_extras_subpkg: Add long options support
 - %%pyproject_extras_subpkg: Make -D/--dist-name mutually exclusive with -i/-f/-F
+- Set PIP_CONFIG_FILE=/dev/null by default when invoking pip to build the wheel
 
 * Thu Jul 16 2026 Fedora Release Engineering <releng@fedoraproject.org> - 1.23.0-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild

pyproject_wheel.py

@@ -1,4 +1,5 @@
 import argparse
+import os
 import sys
 import subprocess
 
@@ -56,7 +57,8 @@ def build_wheel(*, wheeldir, stdout=None, config_settings=None):
         *get_config_settings_args(config_settings),
         '.',
     )
-    cp = subprocess.run(command, stdout=stdout)
+    env = {'PIP_CONFIG_FILE': '/dev/null', **os.environ}
+    cp = subprocess.run(command, env=env, stdout=stdout)
     return cp.returncode