Reraise exception with modified stack

[Nicolas Fleury]

Scott David Daniels wrote:
> How about dropping reraise and changing:
>           reraise(...)
> to:
>           addinfo(...)
>           raise

It doesn't work, or at least it doesn't do what I want.  I want to keep 
the same exception stack to be able to identify the original error.  I 
would like to avoid also writing in the caller something like 
sys.exc_info()[-1].

Regards,
Nicolas