I know creating an IntVector from a set is not an immensely useful feature. I had in fact done so on accident. But the segfault made the bug harder to track down than I would have wished...
I'm using Python 2.7.12, rpy2 2.8.5, and R 3.2.3, on Ubuntu 16.04.2 LTS.
To reproduce the segmentation fault:
from rpy2.robjects import IntVector IntVector(set((0, 1)))