Comment 4 for bug 1233645

StacktraceTop:
 __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7fd154363740 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:199
 malloc_printerr (ptr=0x7fd120001dc0, str=0x7fd15435f732 "invalid fastbin entry (free)", action=3) at malloc.c:4923
 _int_free (av=<optimized out>, p=0x7fd120001db0, have_lock=0) at malloc.c:3779
 cleanreturn (freelist=0x7fd1361ef590, retval=1) at ../Python/getargs.c:190
 vgetargskeywords.17836 (args=<optimized out>, keywords=keywords@entry=0x0, format=0x63e6d2 "ss:str", format@entry=0x63e6d0 "|Oss:str", kwlist=kwlist@entry=0x98e480 <kwlist.17886.10037.5521>, p_va=p_va@entry=0x7fd1361ef860, flags=flags@entry=2) at ../Python/getargs.c:1603