Extend last change to cover TestSuites as well as TestCases.

Lib/test/test_support.py

@@ -251,7 +251,7 @@ def run_unittest(*classes):
     """Run tests from unittest.TestCase-derived classes."""
     suite = unittest.TestSuite()
     for cls in classes:
-        if isinstance(cls, unittest.TestCase):
+        if isinstance(cls, (unittest.TestSuite, unittest.TestCase)):
             suite.addTest(cls)
         else:
             suite.addTest(unittest.makeSuite(cls))