Here is the minimal code to produce the crash on OS X Yosemite, with Python 2.7.9 compiled by homebrew.

# -*- coding: utf-8 -*-
import numpy
import matplotlib.pyplot as plt
plt.plot(numpy.linspace(0, 1, 1000), numpy.random.randn(1000))
plt.savefig('test.jpg')
plt.show()

The error message is

Assertion failed: (s->stack->next != NULL), function CGGStackRestore, file Context/CGGStack.c, line 77.

The crash does not happen if the savefig and show call are swapped, or when saving to png/pdf/svg file. It only happens when pyplot is called in this sequence, and when the format is jpg.