SF #532767: isinstance(x, X) should work when x is a proxy for an X
instance, as long as x.__class__ is X or a subclass thereof.
Did a little cleanup of PyObject_IsInstance() too.
diff --git a/Misc/NEWS b/Misc/NEWS
index ed4f7cf..d88f753 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,11 @@
Core and builtins
-----------------
+- isinstance(x, X): if X is a new-style class, this is now equivalent
+ to issubclass(type(x), X) or issubclass(x.__class__, X). Previously
+ only type(x) was tested. (For classic classes this was already the
+ case.)
+
- compile(), eval() and the exec statement now fully support source code
passed as unicode strings.