xfail test_pip_wheel_ext_module_with_tmpdir_inside

This test fails for unexplained reasons only on MacOS and
python 3.7 and 3.8.

Author: sbidoul

tests/functional/test_wheel.py

@@ -342,6 +342,14 @@ def test_pip_wheel_with_user_set_in_config(
     sys.platform.startswith("win"),
     reason="The empty extension module does not work on Win",
 )
+@pytest.mark.xfail(
+    condition=sys.platform == "darwin" and sys.version_info < (3, 9),
+    reason=(
+        "Unexplained 'no module named platform' in "
+        "https://github.com/pypa/packaging/blob/"
+        "5b34465682d40ddd42dd6cba88e158e1674de7b9/src/packaging/tags.py#L396-L411"
+    ),
+)
 def test_pip_wheel_ext_module_with_tmpdir_inside(
     script: PipTestEnvironment, data: TestData, common_wheels: Path
 ) -> None: