In python 2.5.2 on ubuntu Ibex. If your run the command python round_robin_seg.py smallest_tomog. Using the files provided. There is a segfault. It happens in the core interpreter. It happened when I added line 35 to the python code. Sorry I do not have time at the moment to pin it down better.
Hmm I just remembered I was using psyco with this code. With out it. There is a recursion depth exception not a segfault. Changing the bug to be in Extension modules. If that is the right place.