Fix lint error.

Author: serhiy-storchaka

Lib/test/picklecommon.py

@@ -93,7 +93,7 @@ def __reduce_ex__(self, proto):
         self._proto = proto
         return REX_two, ()
     def __reduce__(self):
-        raise TestFailed("This __reduce__ shouldn't be called")
+        raise AssertionError("This __reduce__ shouldn't be called")
 
 class REX_four(object):
     """Calling base class method should succeed"""

Lib/test/pickletester.py

@@ -27,7 +27,7 @@
 from test import support
 from test.support import os_helper
 from test.support import (
-    TestFailed, run_with_locales, no_tracing,
+    run_with_locales, no_tracing,
     _2G, _4G, bigmemtest
     )
 from test.support.import_helper import forget