Invalid reads according to valgrind (MoarVM Issuer #234) (32k nursery)

gistfile1.txt

dogbert@dogbert-VirtualBox ~/repos/rakudo $ cat ~/scratch.pl6
for ^1000 { IO::Socket::INET.new( :port($_), :host("127.0.0.1") ); CATCH {next}; say $_~" is open" }

dogbert@dogbert-VirtualBox ~/repos/rakudo $ ./perl6-valgrind-m ~/scratch.pl6 
================================================================================================
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 2017.01.10.gc.3.c.86.dcf.5 built on MoarVM version 2017.01,
running on ubuntu (14.04.3.LTS.Trusty.Tahr) / linux (3.19.0.32.generic)
------------------------------------------------------------------------------------------------
==29559== Memcheck, a memory error detector
==29559== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==29559== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==29559== 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 /home/dogbert/scratch.pl6
==29559== 
139 is open
445 is open
==29559== Invalid read of size 4
==29559==    at 0x41EDC8F: uv__platform_invalidate_fd (in /home/dogbert/repos/rakudo/install/lib/libmoar.so)
==29559==    by 0x41F303C: uv__io_close (in /home/dogbert/repos/rakudo/install/lib/libmoar.so)
==29559==    by 0x41FB3F7: uv__stream_close (in /home/dogbert/repos/rakudo/install/lib/libmoar.so)
==29559==    by 0x41FBDBA: uv__tcp_close (in /home/dogbert/repos/rakudo/install/lib/libmoar.so)
==29559==    by 0x41F2287: uv_close (in /home/dogbert/repos/rakudo/install/lib/libmoar.so)
==29559==    by 0x4131D29: do_close (syncsocket.c:24)
==29559==    by 0x4131DAD: gc_free (syncsocket.c:40)
==29559==    by 0x4157F6D: gc_free (MVMOSHandle.c:48)
==29559==    by 0x4129D73: MVM_gc_collect_free_nursery_uncopied (collect.c:580)
==29559==    by 0x4122C53: run_gc (orchestrate.c:352)
==29559==    by 0x4122FF1: MVM_gc_enter_from_allocator (orchestrate.c:462)
==29559==    by 0x412330E: MVM_gc_allocate_nursery (allocation.c:32)
==29559==  Address 0xbeb6a684 is on thread 1's stack
==29559==  11772 bytes below stack pointer
==29559== 
631 is open
==29559== 
==29559== HEAP SUMMARY:
==29559==     in use at exit: 28,174,788 bytes in 261,766 blocks
==29559==   total heap usage: 707,652 allocs, 445,886 frees, 170,515,969 bytes allocated
==29559== 
==29559== LEAK SUMMARY:
==29559==    definitely lost: 82,526 bytes in 2,122 blocks
==29559==    indirectly lost: 29,216 bytes in 2,565 blocks
==29559==      possibly lost: 2,532,178 bytes in 53,923 blocks
==29559==    still reachable: 25,530,868 bytes in 203,156 blocks
==29559==         suppressed: 0 bytes in 0 blocks
==29559== Rerun with --leak-check=full to see details of leaked memory
==29559== 
==29559== For counts of detected and suppressed errors, rerun with: -v
==29559== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)