I don't have a particularly minimal test case for this, however I am able to reproduce it consistently (so far reproduced on multiple machines, 32-bit and 64-bit on 2.6 and 2.7), using these steps:

First get a checkout of the PyPy repository:

hg clone ssh://hg@bitbucket.org/pypy/pypy

Next, get to the correct revision:

hg up -C 82e1fc9c253c

Finally, attempt to run the tests:

./pytest.py pypy/module/micronumpy/ -x

At this point you should have a segfault that appears to be because of a bad address for a weakref (but I could be horrifically wrong).