Change the PyUnit-based tests to use the test_main() approach.  This
allows using the tests with unittest.py as a script.  The tests will
still run when run as a script themselves.
diff --git a/Lib/test/test_mailbox.py b/Lib/test/test_mailbox.py
index 57a8316..4e23398 100644
--- a/Lib/test/test_mailbox.py
+++ b/Lib/test/test_mailbox.py
@@ -96,4 +96,9 @@
     # XXX We still need more tests!
 
 
-test_support.run_unittest(MaildirTestCase)
+def test_main():
+    test_support.run_unittest(MaildirTestCase)
+
+
+if __name__ == "__main__":
+    test_main()