Someone pointed out on HN that Python gives segfault. He used a = 1000, a/1000 example. I did it on Python 3 and got the same error. It worked on Python 2 that came with Mavericks but thats about it. I'd think there are more issues.
I don't know why they should be, but when I restarted my computer after the update I was greeted with a big fat broken virtualenv install, so I wrote this guide to help anyone else with the same problems.