injecting "set" into 2.3's builtins?

[Skip Montanaro]

    >> caused problems in the past. A module might sniff for 'set' and
    >> assume it is running on 2.4 if it sees it, with unpredictable results
    >> if it relies on any other 2.4 behaviour.

    John> Aarrgghh! When there's a documented API (sys.version_info) for
    John> determining the version, such a module (and it's author) could be
    John> charitably described as "broken". I can't imagine there are any on
    John> Skip's site :-)

Thanks for the vote of confidence (I think).  Yes, I'd only inject "set"
into builtins on 2.3, and anyone who wants to do version-dependent things
should use some variant of sys.version_info.

Skip