Sorting by item_in_another_list

[bearophileHUGS at lycos.com]

Carsten Haese:
> However, it's not clear
> whether this specifies language behavior that all implementations must
> adhere to, or whether it simply documents an implementation detail of
> CPython.

I think it's CPython-specific, but maybe here people expert in Jython
and IronPython can tell if their sort is stable.

Bye,
bearophile