expected failure should not trigger failfast behavior in unittest.

Lib/test/test_unittest.py

@@ -2113,12 +2113,6 @@ class Test_TestResult(TestCase):
         result.addUnexpectedSuccess(None)
         self.assertTrue(result.shouldStop)
 
-        result = unittest.TestResult()
-        result._exc_info_to_string = lambda *_: ''
-        result.failfast = True
-        result.addExpectedFailure(None, None)
-        self.assertTrue(result.shouldStop)
-
     def testFailFastSetByRunner(self):
         runner = unittest.TextTestRunner(stream=StringIO(), failfast=True)
         def test(result):

Lib/unittest/main.py

@@ -178,7 +178,7 @@ class TestProgram(object):
                 testRunner = self.testRunner(verbosity=self.verbosity,
                                              failfast=self.failfast)
             except TypeError:
-                # didn't accept the verbosity or failfast argument
+                # didn't accept the verbosity or failfast arguments
                 testRunner = self.testRunner()
         else:
             # it is assumed to be a TestRunner instance

Lib/unittest/result.py

@@ -81,7 +81,6 @@ class TestResult(object):
         """Called when a test is skipped."""
         self.skipped.append((test, reason))
 
-    @failfast
     def addExpectedFailure(self, test, err):
         """Called when an expected failure/error occured."""
         self.expectedFailures.append(