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_mimetypes.py b/Lib/test/test_mimetypes.py
index 9b9d339..8735e27 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -39,4 +39,9 @@
                          ".pyunit")
 
 
-test_support.run_unittest(MimeTypesTestCase)
+def test_main():
+    test_support.run_unittest(MimeTypesTestCase)
+
+
+if __name__ == "__main__":
+    test_main()