> I'm fine with not changing this

Thanks Brett.  I'm going to mark this as closed/rejected.  After five years, it is time to put it to rest and let it stop consuming our mental clock cycles.

> I don't think you're guaranteed to have access to the object
> that triggered the ValueError.

I'm not sure I follow what you're saying.  To call index() or remove() you already have to have the object to search for.   The ValueError is raised when the searched for object is not found, not by some unknown object inside the container.