Sorry for late reply. And, the shown example was a little arbitrary.

That's a fix for [issue 8667](http://d.puremagic.com/issues/show_bug.cgi?id=8667) (until now I couldn't find the issue number), not implementation details. Current selective import unexpectedly modify an overload set that in imported scope, as a side effect. I think that it's not generic, and less orthogonality.