Message903

In Jython 2.3a0, (as in Python 2.3) the 
WeakValueDictionary.__makeremove method in Lib/weakref.py 
relies on being able to make a weakref of self. In Jython, this 
raises an exception, because _weakref.ref(x) requires x to be 
hashable (which WeakValueDictionary is not). In Python, 
_weakref.ref(x) works on unhashable objects.

The problem did not arise in Jython 2.1, as the code in Lib/weakref  
did not try to create a weakref to itself (and so resulted in hash 
tables containing circular references).

Possible fixes off the top of my head:

(better) Fix _weakref.java so it doesn't require a hashable object.

(easier) Don't bother creating a weakref to self in 
WeakValueDictionary.__makeremove since Jython can GC circular 
references.

There are probably similar problems in other parts of weakref.py