Another fromspace error

gistfile1.txt

It appears *sometimes* when running t/spec/S09-typed-arrays/native-num.rakudo.moar with a very small nursery, i.e. less than one k bytes.

ok 446 - List-assign num64 array surrounded by lits (1)
ok 447 - List-assign num64 array surrounded by lits (2)
ok 448 - List-assign num64 array surrounded by lits (3)
ok 449 - List-assign num64 array surrounded by lits (4)
ok 450 - List-assign num64 array surrounded by lits (5)
ok 451 - List-assign array of Num to num64 array (1)
ok 452 - List-assign array of Num to num64 array (2)
ok 453 - List-assign array of Num to num64 array (3)
    1..2
    ok 1 - code dies
    ok 2 - right exception type (Exception)
ok 454 - List-assigning incompatible untyped array to num64 array dies
ok 455 - Smartmatching same num64 arrays works
ok 456 - Smartmatching different num64 arrays works
ok 457 - did we survive the hole
# FUDGED!

Thread 1 "moar" hit Breakpoint 2, __GI_exit (status=0) at exit.c:104
104	exit.c: No such file or directory.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff651d700 (LWP 8815)]

Thread 1 "moar" hit Breakpoint 1, MVM_panic (exitCode=1, messageFormat=0x7ffff7636e90 "Collectable %p in fromspace accessed") at src/core/exceptions.c:832
832	MVM_NO_RETURN void MVM_panic(MVMint32 exitCode, const char *messageFormat, ...) {
(gdb) bt
#0  MVM_panic (exitCode=1, messageFormat=0x7ffff7636e90 "Collectable %p in fromspace accessed") at src/core/exceptions.c:832
#1  0x00007ffff74be6e6 in set_str (tc=0x604ac0, st=0x66f3a8, root=0x604ea0, data=0x604eb8, value=0x6bee88) at src/6model/reprs/P6str.c:28
#2  0x00007ffff73ffd30 in MVM_args_set_result_str (tc=0x604ac0, result=0x6bee88, frameless=0) at src/core/args.c:591
#3  0x00007ffff74095c1 in MVM_interp_run (tc=0x604ac0, initial_invoke=0x7ffff75c5181 <toplevel_initial_invoke>, invoke_data=0x6a2df8) at src/core/interp.c:524
#4  0x00007ffff75c531f in MVM_vm_run_file (instance=0x604010, filename=0x7fffffffe196 "/home/dogbert/repos/rakudo/perl6.moarvm") at src/moar.c:459
#5  0x00000000004016e7 in main (argc=10, argv=0x7fffffffdd08) at src/main.c:302
(gdb) f 1
#1  0x00007ffff74be6e6 in set_str (tc=0x604ac0, st=0x66f3a8, root=0x604ea0, data=0x604eb8, value=0x6bee88) at src/6model/reprs/P6str.c:28
28	    MVM_ASSIGN_REF(tc, &(root->header), ((MVMP6strBody *)data)->value, value);
(gdb) p value
$1 = (MVMString *) 0x6bee88
(gdb) p *value
$2 = {common = {header = {sc_forward_u = {forwarder = 0x604e00, sc = {sc_idx = 6311424, idx = 0}, st = 0x604e00}, owner = 1, flags = 128, size = 48}, st = 0x66efc0}, body = {storage = {blob_32 = 0x392f6e0, blob_ascii = 0x392f6e0 "\320\314", <incomplete sequence \342>, blob_8 = 0x392f6e0 "\320\314", <incomplete sequence \342>, strands = 0x392f6e0, any = 0x392f6e0}, storage_type = 3, num_strands = 1, num_graphs = 5, cached_hash_code = 0}}
(gdb) c
Continuing.
MoarVM panic: Collectable 0x6bee88 in fromspace accessed