The problem is (if I'm understanding this correctly, which I may not be, I'm not a unicode expert) is that how you compute and manipulate CJK characters in python2 differs depending on whether you are dealing with a wide build or a narrow build.  And the fact that python3 doesn't handle it either is why this would be a new feature (see the referenced issues).

But I could be wrong.  I leave it to the unicode experts.