Removed exception renaming cruft in pickle.py.
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 8a8e623..8f1f9f0 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -1308,9 +1308,6 @@
     from _pickle import *
 except ImportError:
     Pickler, Unpickler = _Pickler, _Unpickler
-    PickleError = _PickleError
-    PicklingError = _PicklingError
-    UnpicklingError = _UnpicklingError
 
 # Shorthands