When you type /shutdown and gdb is on this happens:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 malloc_consolidate (av=av@entry=0x7f9b64000020) at malloc.c:4151
4151 malloc.c: No such file or directory.
(gdb) bt
#0 malloc_consolidate (av=av@entry=0x7f9b64000020) at malloc.c:4151
#1 0x00007f9b6ed21691 in _int_free (av=0x7f9b64000020, p=,
have_lock=0) at malloc.c:4057
#2 0x00007f9b6ecdfbc9 in __run_exit_handlers (status=0,
listp=0x7f9b6f04b5a8 <__exit_funcs>,
run_list_atexit=run_list_atexit@entry=true) at exit.c:82
#3 0x00007f9b6ecdfc15 in __GI_exit (status=) at exit.c:104
#4 0x00007f9b6ecc9b4c in __libc_start_main (
main=0x416bc0 <main(int, char**)>, argc=4, argv=0x7fff109c3418,
init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>,
stack_end=0x7fff109c3408) at libc-start.c:321
#5 0x000000000041a900 in _start ()