I've been getting sporadic SIGSEGV crashes in _heapqmodule.c

I have not be able to reliably reproduce it, but here is a stacktrace:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x2aaaad51d940 (LWP 13976)]
(gdb) where
#0  0x00002aaaab617e8a in _siftdown (heap=0xa1f2d8, startpos=0, pos=46)
    at [...]/Python-2.7.2/Modules/_heapqmodule.c:67
#1  0x00002aaaab617f76 in heappush (self=<value optimized out>, args=<value optimized out>)
    at [...]/Python-2.7.2/Modules/_heapqmodule.c:137
#2  0x000000000049ba34 in call_function (f=0xa565e0, throwflag=<value optimized out>) at Python/ceval.c:4013
#3  PyEval_EvalFrameEx (f=0xa565e0, throwflag=<value optimized out>) at Python/ceval.c:2666
#4  0x000000000049ca8d in call_function (f=0xa60f40, throwflag=<value optimized out>) at Python/ceval.c:4099
#5  PyEval_EvalFrameEx (f=0xa60f40, throwflag=<value optimized out>) at Python/ceval.c:2666
#6  0x000000000049ca8d in call_function (f=0xa5e210, throwflag=<value optimized out>) at Python/ceval.c:4099
#7  PyEval_EvalFrameEx (f=0xa5e210, throwflag=<value optimized out>) at Python/ceval.c:2666
#8  0x000000000049ca8d in call_function (f=0xa5e020, throwflag=<value optimized out>) at Python/ceval.c:4099
#9  PyEval_EvalFrameEx (f=0xa5e020, throwflag=<value optimized out>) at Python/ceval.c:2666
#10 0x000000000049ca8d in call_function (f=0xa5de00, throwflag=<value optimized out>) at Python/ceval.c:4099
#11 PyEval_EvalFrameEx (f=0xa5de00, throwflag=<value optimized out>) at Python/ceval.c:2666
#12 0x000000000049ca8d in call_function (f=0xa5dc30, throwflag=<value optimized out>) at Python/ceval.c:4099
#13 PyEval_EvalFrameEx (f=0xa5dc30, throwflag=<value optimized out>) at Python/ceval.c:2666
#14 0x000000000049d87b in PyEval_EvalCodeEx (co=0x896530, globals=<value optimized out>, locals=<value optimized out>,
    args=0x99dba8, argcount=1, kws=0x0, kwcount=0, defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:3253
#15 0x00000000004fbf9f in function_call (func=0x8c30c8, arg=0x99db90, kw=0x0) at Objects/funcobject.c:526
#16 0x000000000041882d in PyObject_Call (func=0x8c30c8, arg=0x99db90, kw=0x0) at Objects/abstract.c:2529
#17 0x000000000041fd3f in instancemethod_call (func=<value optimized out>, arg=0x99db90, kw=0x0)
    at Objects/classobject.c:2578
#18 0x000000000041882d in PyObject_Call (func=0x2aaaaab7e730, arg=0x2aaaaaabc050, kw=0x0) at Objects/abstract.c:2529
#19 0x0000000000494a66 in PyEval_CallObjectWithKeywords (func=0x2aaaaab7e730, arg=0x2aaaaaabc050, kw=0x0)
    at Python/ceval.c:3882
#20 0x00000000004d30d2 in t_bootstrap (boot_raw=0x96d320) at ./Modules/threadmodule.c:614
#21 0x0000003fa780683d in start_thread () from /lib64/libpthread.so.0
#22 0x0000003fa6cd503d in clone () from /lib64/libc.so.6