strange error whilst porting to 2.6

[Robin Becker]

Steve Holden wrote:
> Benjamin Peterson wrote:
>> Robin Becker <robin <at> NOSPAMreportlab.com> writes:
>>> Well that's not really acceptable as a solution is it? :)
>> This doesn't happen in Python 3.0,
>> so you could port to that. :)

my initial attempts in this direction were even less successful :(


........
> Perhaps an interim solution would implement an error message more
> helpful in ensuring the exception not be raised? This is currently a bit
> like "Your code is wrong": strictly correct, and totally unhelpful.


well after wrapping all the calls to isinstance I think I have found the 
  particular call and args that are causing the problem, but I still 
don't really understand why the problem is occurring.
-- 
Robin Becker