Yup, this is similar to ruby-contract -- but still, I think that wrappers are not always the best solution to problems. If a good implementation of selector namespaces can be found I think it is besser for solving this specific problem. (Even though it has not been a serious problem so far. -- I guess it is part of the Ruby mindset that being tolerant is usually a good idea, even if it might mean that you can step onto others toes.)
In practice most Python programmers get by just fine when they do stuff that risks name collision. Some people say it's just because the applications are small and reuse not that common; and it's people with an eye to big systems (like Zope 3 people) that are pushing for more isolation. I'm still not sure if it's easier just to deal with problems when they occur, instead of trying to avoid all possible conflicts. Especially in an open-source ecosystem -- when all code is open to change, and there is no "my code" and "not my code" -- I think problem-avoidance isn't as important as intelligent and cooperative problem-solving. And of course we both have the option to monkey patch (fix the code in-process, instead of on-disk).