rusti segfaults when spawning a new task

[danluu]

rusti> spawn( || println("Please don't segfault") ); () Segmentation fault: 11

rusti> do spawn { println("Please?"); } () Segmentation fault: 11

Reason: KERN_PROTECTION_FAILURE at address: 0x00000001038074b8
[Switching to process 89585 thread 0x1d03]
0x00000001038074b8 in ?? ()
(gdb) bt
#0  0x00000001038074b8 in ?? ()
#1  0x0000000100105112 in __morestack ()
#2  0x00000001000847dc in task::spawn::spawn_raw::make_child_wrapper::anon::expr_fn_11924 ()```