Address review: simplify condition, use import_fresh_module, update NEWS

Per @vstinner:
- Simplify to 'if _pkg_dir:' instead of walrus + is not None
- Replace mock-based test with import_fresh_module for both '' and None
- Reword NEWS to describe old behavior instead of fix

Author: kimimgo

Lib/ensurepip/__init__.py

@@ -16,7 +16,8 @@
 # policies recommend against bundling dependencies. For example, Fedora
 # installs wheel packages in the /usr/share/python-wheels/ directory and don't
 # install the ensurepip._bundled package.
-if (_pkg_dir := sysconfig.get_config_var('WHEEL_PKG_DIR')) is not None and _pkg_dir:
+_pkg_dir = sysconfig.get_config_var('WHEEL_PKG_DIR')
+if _pkg_dir:
     _WHEEL_PKG_DIR = Path(_pkg_dir).resolve()
 else:
     _WHEEL_PKG_DIR = None

Lib/test/test_ensurepip.py

@@ -7,6 +7,7 @@
 import unittest
 import unittest.mock
 from pathlib import Path
+from test.support import import_helper
 
 import ensurepip
 import ensurepip._uninstall
@@ -36,12 +37,14 @@ def test_version_no_dir(self):
             # when the bundled pip wheel is used, we get _PIP_VERSION
             self.assertEqual(ensurepip._PIP_VERSION, ensurepip.version())
 
-    def test_empty_wheel_pkg_dir_treated_as_none(self):
-        # GH#146310: empty string WHEEL_PKG_DIR should not search CWD.
-        # An empty WHEEL_PKG_DIR converts to Path('.') which would
-        # incorrectly search the current working directory.
-        with unittest.mock.patch.object(ensurepip, '_WHEEL_PKG_DIR', None):
-            self.assertIsNone(ensurepip._find_wheel_pkg_dir_pip())
+    def test_wheel_pkg_dir_none(self):
+        # GH#146310: empty or None WHEEL_PKG_DIR should not search CWD
+        for value in ('', None):
+            with unittest.mock.patch('sysconfig.get_config_var',
+                                     return_value=value) as get_config_var:
+                module = import_helper.import_fresh_module('ensurepip')
+                self.assertIsNone(module._WHEEL_PKG_DIR)
+                get_config_var.assert_called_once_with('WHEEL_PKG_DIR')
 
     def test_selected_wheel_path_no_dir(self):
         pip_filename = f'pip-{ensurepip._PIP_VERSION}-py3-none-any.whl'

Misc/NEWS.d/next/Library/2026-03-24-03-49-50.gh-issue-146310.WhlDir.rst

@@ -1,2 +1,2 @@
-Fix :mod:`ensurepip` to treat an empty string ``WHEEL_PKG_DIR`` as unset,
-preventing it from searching the current working directory for wheel files.
+The :mod:`ensurepip` module no longer looks for ``pip-*.whl`` wheel packages
+in the current directory.