Well, I've only tried that one example for now, and because of the results, I just thought to put a warning out. I didn't expect the language to have changed completly between those two versions (afterall, it's still the same language...) but it would suck pretty bad if you learned 2.6 and while modding you learned that everything you tried would generate errors...
So, better safe than sorry I guess
There's actually a tool that automatically converts Python 2.x code to Python 3.x code:
It works fairly well (things that I've translated with it have needed only minor tweaks afterwards to get them fully working again)
On a side note, noticed that 'code blocks' don't include support for either Java or Python. Since Elemental's AI dev is going to be in Python, it would probably make sense to add Python support to code blocks too.