Issue #20589: Invoking Path.owner() and Path.group() on Windows now raise

NotImplementedError instead of ImportError.

Lib/test/test_pathlib.py

@@ -1156,6 +1156,15 @@ class PureWindowsPathTest(_BasePurePathTest, unittest.TestCase):
         # UNC paths are never reserved
         self.assertIs(False, P('//my/share/nul/con/aux').is_reserved())
 
+    def test_owner(self):
+        P = self.cls
+        with self.assertRaises(NotImplementedError):
+            P('c:/').owner()
+
+    def test_group(self):
+        P = self.cls
+        with self.assertRaises(NotImplementedError):
+            P('c:/').group()
 
 class PurePathTest(_BasePurePathTest, unittest.TestCase):
     cls = pathlib.PurePath