Fix issue 9926. TestSuite subclasses that override __call__ are called correctly.
diff --git a/Lib/unittest/result.py b/Lib/unittest/result.py
index 1dbd04c..3dc7154 100644
--- a/Lib/unittest/result.py
+++ b/Lib/unittest/result.py
@@ -34,6 +34,7 @@
     formatted traceback of the error that occurred.
     """
     _previousTestClass = None
+    _testRunEntered = False
     _moduleSetUpFailed = False
     def __init__(self, stream=None, descriptions=None, verbosity=None):
         self.failfast = False