Rakudo bug

Bug.pm6

my role IO { ... }
my class IO::VMHandle is repr<MVMOSHandle> { method new {} }
my role IO {}
# IO::<VMHandle> := IO::VMHandle;
sub EXPORT { Map.new((IO => IO)) }

cmdline

$ perl6 -I. -MBug -e 'say IO::VMHandle.^name; IO::VMHandle.new'
NQPMu

# uncomment line in Bug.pm6
$ perl6 -I. -MBug -e 'say IO::VMHandle.^name; IO::VMHandle.new'
IO::VMHandle
Internal error: inconsistent bind result
  in method new at D:\dev\p6\newio\Bug.pm (Bug) line 2
  in block <unit> at -e line 1

moar.patch

diff --git a/src/6model/reprs/MVMOSHandle.c b/src/6model/reprs/MVMOSHandle.c
index fe24d4d..284af9f 100644
--- a/src/6model/reprs/MVMOSHandle.c
+++ b/src/6model/reprs/MVMOSHandle.c
@@ -68,6 +68,27 @@ static const MVMStorageSpec * get_storage_spec(MVMThreadContext *tc, MVMSTable *
     return &storage_spec;
 }
 
+/* Performs a change of type, where possible. */
+static void change_type(MVMThreadContext *tc, MVMObject *obj, MVMObject *new_type) {
+    /* Ensure we don't have a type object. */
+    if (!IS_CONCRETE(obj))
+        MVM_exception_throw_adhoc(tc,
+            "Cannot change the type of a type object");
+
+    /* Ensure that the REPR of the new type is also MVMOSHandle. */
+    if (REPR(new_type)->ID != REPR(obj)->ID)
+        MVM_exception_throw_adhoc(tc,
+            "New type must have a matching representation");
+
+    /* Switch over the STable. */
+    MVM_ASSIGN_REF(tc, &(obj->header), obj->st, STABLE(new_type));
+}
+
+/* Set the size of the STable. */
+static void deserialize_stable_size(MVMThreadContext *tc, MVMSTable *st, MVMSerializationReader *reader) {
+    st->size = sizeof(MVMOSHandle);
+}
+
 /* Compose the representation. */
 static void compose(MVMThreadContext *tc, MVMSTable *st, MVMObject *info) {
     /* Nothing to do for this REPR. */
@@ -89,12 +110,12 @@ static const MVMREPROps this_repr = {
     MVM_REPR_DEFAULT_ASS_FUNCS,
     MVM_REPR_DEFAULT_ELEMS,
     get_storage_spec,
-    NULL, /* change_type */
+    change_type,
     NULL, /* serialize */
     NULL, /* deserialize */
     NULL, /* serialize_repr_data */
     NULL, /* deserialize_repr_data */
-    NULL, /* deserialize_stable_size */
+    deserialize_stable_size,
     gc_mark,
     gc_free,
     NULL, /* gc_cleanup */