Make sure each test can be run standalone (./python Lib/distutils/tests/x.py)
diff --git a/Lib/distutils/tests/test_dir_util.py b/Lib/distutils/tests/test_dir_util.py
index aa9f9eb..7356c76 100644
--- a/Lib/distutils/tests/test_dir_util.py
+++ b/Lib/distutils/tests/test_dir_util.py
@@ -10,6 +10,7 @@
 
 from distutils import log
 from distutils.tests import support
+from test.support import run_unittest
 
 class DirUtilTestCase(support.TempdirManager, unittest.TestCase):
 
@@ -112,4 +113,4 @@
     return unittest.makeSuite(DirUtilTestCase)
 
 if __name__ == "__main__":
-    unittest.main(defaultTest="test_suite")
+    run_unittest(test_suite())