pythongh-120418: Don't assume wheeldata is deleted if WHEEL_PKG_DIR is set (python#120419)

Remove wheeldata from both sides of the `assertEqual`, so that we're
*actually* ignoring it from the test set.

This test is only making assertions about the source tree, no code is
being executed that would do anything different based on the value of
`WHEEL_PKG_DIR`.

Author: stefanor

Lib/test/test_tools/test_makefile.py

@@ -41,7 +41,7 @@ def test_makefile_test_folders(self):
         idle_test = 'idlelib/idle_test'
         self.assertIn(idle_test, test_dirs)
 
-        used = [idle_test]
+        used = set([idle_test])
         for dirpath, dirs, files in os.walk(support.TEST_HOME_DIR):
             dirname = os.path.basename(dirpath)
             # Skip temporary dirs:
@@ -65,13 +65,14 @@ def test_makefile_test_folders(self):
                         "of test directories to install"
                     )
                 )
-                used.append(relpath)
+                used.add(relpath)
 
         # Don't check the wheel dir when Python is built --with-wheel-pkg-dir
         if sysconfig.get_config_var('WHEEL_PKG_DIR'):
             test_dirs.remove('test/wheeldata')
+            used.discard('test/wheeldata')
 
         # Check that there are no extra entries:
         unique_test_dirs = set(test_dirs)
-        self.assertSetEqual(unique_test_dirs, set(used))
+        self.assertSetEqual(unique_test_dirs, used)
         self.assertEqual(len(test_dirs), len(unique_test_dirs))