fails initializing objects with native nums iff Test.pm is loaded

gistfile1.txt

diff --git a/src/core/Mu.pm b/src/core/Mu.pm
index d34ae40..8beed17 100644
--- a/src/core/Mu.pm
+++ b/src/core/Mu.pm
@@ -112,6 +112,7 @@ Please refactor this code using the new Iterator / Seq interface.
     }
 
     method BUILDALL(@autovivs, %attrinit) {
+        my $init := nqp::getattr(%attrinit,Map,'$!storage');
         # Get the build plan. Note that we do this "low level" to
         # avoid the NQP type getting mapped to a Rakudo one, which
         # would get expensive.
@@ -127,26 +128,22 @@ Please refactor this code using the new Iterator / Seq interface.
                 nqp::atpos($task, 1)(self, |%attrinit);
             }
             elsif nqp::iseq_i($code, 1) {
-                # See if we have a value to initialize this attr
-                # with.
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
+                # See if we have a value to initialize this attr with.
                 nqp::getattr(self,nqp::atpos($task,1),nqp::atpos($task,3))
-                  = %attrinit.AT-KEY($key_name)
-                  if %attrinit.EXISTS-KEY($key_name);
+                  = %attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2)))
+                  if nqp::existskey($init,nqp::atpos($task,2));
             }
             elsif nqp::iseq_i($code, 2) {
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
-                %attrinit.EXISTS-KEY($key_name)
+                nqp::existskey($init,nqp::atpos($task,2))
                   ?? (nqp::getattr(self,nqp::atpos($task,1),nqp::atpos($task,3))
-                       = %attrinit.AT-KEY($key_name))
+                       = %attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2))))
                   !! nqp::bindattr(self,nqp::atpos($task,1),nqp::atpos($task,3),
                        nqp::list);
             }
             elsif nqp::iseq_i($code, 3) {
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
-                %attrinit.EXISTS-KEY($key_name)
+                nqp::existskey($init,nqp::atpos($task,2))
                   ?? (nqp::getattr(self,nqp::atpos($task,1),nqp::atpos($task,3))
-                       = %attrinit.AT-KEY($key_name))
+                       = %attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2))))
                   !! nqp::bindattr(self,nqp::atpos($task,1),nqp::atpos($task,3),
                        nqp::hash);
             }
@@ -157,22 +154,19 @@ Please refactor this code using the new Iterator / Seq interface.
                 }
             }
             elsif nqp::iseq_i($code, 5) {
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
                 nqp::bindattr_i(self,nqp::atpos($task,1),nqp::atpos($task,3),
-                  nqp::decont(%attrinit.AT-KEY($key_name)))
-                  if %attrinit.EXISTS-KEY($key_name);
+                  nqp::decont(%attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2)))))
+                  if nqp::existskey($init,nqp::atpos($task,2));
             }
             elsif nqp::iseq_i($code, 6) {
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
                 nqp::bindattr_n(self,nqp::atpos($task,1),nqp::atpos($task,3),
-                  nqp::decont(%attrinit.AT-KEY($key_name)))
-                  if %attrinit.EXISTS-KEY($key_name);
+                  nqp::decont(%attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2)))))
+                  if nqp::existskey($init,nqp::atpos($task,2));
             }
             elsif nqp::iseq_i($code, 7) {
-                my $key_name := nqp::p6box_s(nqp::atpos($task, 2));
                 nqp::bindattr_s(self,nqp::atpos($task,1),nqp::atpos($task,3),
-                  nqp::decont(%attrinit.AT-KEY($key_name)))
-                  if %attrinit.EXISTS-KEY($key_name);
+                  nqp::decont(%attrinit.AT-KEY(nqp::p6box_s(nqp::atpos($task,2)))))
+                  if nqp::existskey($init,nqp::atpos($task,2));
             }
             elsif nqp::iseq_i($code, 8) {
                 my int $cur_value = nqp::getattr_i(self, nqp::atpos($task, 1), nqp::atpos($task, 2));

gistfile2.txt

$ 6 'class C { has num $.a }; C.new(a => 42e0)'   # golfed, is fine
$ 6l 'use Test; class C { has num $.a }; C.new(a => 42e0)'
P6opaque: invalid kind in attribute bind
   at gen/moar/m-CORE.setting:964  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/./CORE.setting.moarvm::0)
 from gen/moar/m-CORE.setting:964  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/./CORE.setting.moarvm:BUILDALL:85)
 from gen/moar/m-CORE.setting:952  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/./CORE.setting.moarvm:bless:41)
 from gen/moar/m-CORE.setting:939  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/./CORE.setting.moarvm:new:20)
 from gen/moar/m-CORE.setting:937  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/./CORE.setting.moarvm:new:39)
 from -e:1  (<ephemeral file>:<unit>:31)
 from -e:1  (<ephemeral file>:<unit-outer>:10)
 from gen/moar/stage2/NQPHLL.nqp:1304  (/Users/liz/Github/rakudo.moar/install/share/nqp/lib/NQPHLL.moarvm:eval:190)
 from gen/moar/stage2/NQPHLL.nqp:1394  (/Users/liz/Github/rakudo.moar/install/share/nqp/lib/NQPHLL.moarvm::35)
 from gen/moar/stage2/NQPHLL.nqp:1391  (/Users/liz/Github/rakudo.moar/install/share/nqp/lib/NQPHLL.moarvm:command_eval:155)
 from src/Perl6/Compiler.nqp:69  (blib/Perl6/Compiler.moarvm:command_eval:93)
 from gen/moar/stage2/NQPHLL.nqp:1375  (/Users/liz/Github/rakudo.moar/install/share/nqp/lib/NQPHLL.moarvm:command_line:114)
 from gen/moar/m-main.nqp:37  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/perl6.moarvm:MAIN:18)
 from gen/moar/m-main.nqp:33  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/perl6.moarvm:<mainline>:189)
 from <unknown>:1  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/perl6.moarvm:<main>:8)
 from <unknown>:1  (/Users/liz/Github/rakudo.moar/install/share/perl6/runtime/perl6.moarvm:<entry>:9)