Oneliner fail on 32 bit system

gistfile1.txt

dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-valgrind-m  -e 'my $sh = <a>.SetHash; for $sh.pairs { .value = 0; .value = 1 }'
================================================================================================
This is Rakudo Perl 6 running in valgrind, a tool for debugging and profiling programs.
Running a program in valgrind usually takes *a lot* more time than running it directly,
so please be patient.
This Rakudo version is 2017.05.91.gf.2.fca.0.c.8.c built on MoarVM version 2017.05.24.gd.86.a.35.b.6,
running on ubuntu (14.04.3.LTS.Trusty.Tahr) / linux (3.19.0.32.generic)
------------------------------------------------------------------------------------------------
==13508== Memcheck, a memory error detector
==13508== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==13508== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==13508== Command: /home/dogbert/repos/rakudo/install/bin/moar --execname=./perl6-ugga --libpath=/home/dogbert/repos/rakudo/install/share/nqp/lib --libpath=/home/dogbert/repos/rakudo/install/share/nqp/lib --libpath=. /home/dogbert/repos/rakudo/perl6.moarvm --nqp-lib=blib -e my\ $sh\ =\ \<a\>.SetHash;\ for\ $sh.pairs\ {\ .value\ =\ 0;\ .value\ =\ 1\ }
==13508== 
==13508== Invalid read of size 4
==13508==    at 0x4149A82: MVM_iterkey_s (MVMIter.c:333)
==13508==    by 0x40DACC0: MVM_interp_run (interp.c:2708)
==13508==    by 0x41C7413: MVM_vm_run_file (moar.c:323)
==13508==    by 0x8048F39: main (main.c:246)
==13508==  Address 0x9cc52c0 is 24 bytes inside a block of size 36 free'd
==13508==    at 0x402B3D8: free (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so)
==13508==    by 0x410C42B: MVM_free (alloc.h:29)
==13508==    by 0x410CC81: MVM_fixed_size_free (fixedsizealloc.c:259)
==13508==    by 0x413A966: delete_key (MVMHash.c:126)
==13508==    by 0x40D8D59: MVM_interp_run (interp.c:2394)
==13508==    by 0x41C7413: MVM_vm_run_file (moar.c:323)
==13508==    by 0x8048F39: main (main.c:246)
==13508== 
==13508== 
==13508== HEAP SUMMARY:
==13508==     in use at exit: 31,354,198 bytes in 271,100 blocks
==13508==   total heap usage: 312,734 allocs, 41,634 frees, 43,842,748 bytes allocated
==13508== 
==13508== LEAK SUMMARY:
==13508==    definitely lost: 0 bytes in 0 blocks
==13508==    indirectly lost: 0 bytes in 0 blocks
==13508==      possibly lost: 2,619,108 bytes in 57,994 blocks
==13508==    still reachable: 28,735,090 bytes in 213,106 blocks
==13508==         suppressed: 0 bytes in 0 blocks
==13508== Rerun with --leak-check=full to see details of leaked memory
==13508== 
==13508== For counts of detected and suppressed errors, rerun with: -v
==13508== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)