fix description of super() behavior on descriptors

Doc/howto/descriptor.rst

@@ -119,7 +119,7 @@ The important points to remember are:
 The object returned by ``super()`` also has a custom :meth:`__getattribute__`
 method for invoking descriptors.  The call ``super(B, obj).m()`` searches
 ``obj.__class__.__mro__`` for the base class ``A`` immediately following ``B``
-and then returns ``A.__dict__['m'].__get__(obj, A)``.  If not a descriptor,
+and then returns ``A.__dict__['m'].__get__(obj, B)``.  If not a descriptor,
 ``m`` is returned unchanged.  If not in the dictionary, ``m`` reverts to a
 search using :meth:`object.__getattribute__`.