run-tests: define cleanup() on unittest class

run-tests: define cleanup() on unittest class

We need a cleanup() on our unittest TestCase class to conform with the
execution API. This will eventually be replaced by tearDown().

--- a/tests/run-tests.py	Sun Apr 20 12:45:44 2014 -0700
+++ b/tests/run-tests.py	Sat May 17 12:35:44 2014 -0700
@@ -1340,6 +1340,10 @@
                 else:
                     self.fail('Unknown test result code: %s' % code)
 
+            # We need this proxy until tearDown() is implemented.
+            def cleanup(self):
+                return t.cleanup()
+
         return MercurialTest(test)
 
     def _cleanup(self):