Fix pathext test for shutil.which() which was

broken after applying the patch for issue #16957.

Lib/test/test_shutil.py

@@ -1338,7 +1338,7 @@ class TestWhich(unittest.TestCase):
     def test_pathext_checking(self):
         # Ask for the file without the ".exe" extension, then ensure that
         # it gets found properly with the extension.
-        rv = shutil.which(self.temp_file.name[:-4], path=self.dir)
+        rv = shutil.which(self.file[:-4], path=self.dir)
         self.assertEqual(rv, self.temp_file.name[:-4] + ".EXE")