Fix up list iteration for FT build

Author: markshannon

Diff for: Python/bytecodes.c

@@ -3196,8 +3196,7 @@ dummy_func(
             EXIT_IF(Py_TYPE(iter_o) != &PyList_Type);
             assert(PyStackRef_IsTaggedInt(null_or_index));
 #ifdef Py_GIL_DISABLED
-            EXIT_IF(!_Py_IsOwnedByCurrentThread(iter_o) ||
-                    !_PyObject_GC_IS_SHARED(iter_o));
+            EXIT_IF(!_Py_IsOwnedByCurrentThread(iter_o) && !_PyObject_GC_IS_SHARED(iter_o));
 #endif
         }
 

Diff for: Python/executor_cases.c.h

@@ -2902,13 +2902,10 @@ _Py_Specialize_ForIter(_PyStackRef iter, _PyStackRef null_or_index, _Py_CODEUNIT
     PyObject *iter_o = PyStackRef_AsPyObjectBorrow(iter);
     PyTypeObject *tp = Py_TYPE(iter_o);
 #ifdef Py_GIL_DISABLED
-    // Only specialize for uniquely referenced iterators, so that we know
-    // they're only referenced by this one thread. This is more limiting
-    // than we need (even `it = iter(mylist); for item in it:` won't get
-    // specialized) but we don't have a way to check whether we're the only
-    // _thread_ who has access to the object.
-    if (!_PyObject_IsUniquelyReferenced(iter_o))
+    // Only specialize for lists owned by this thread or shared
+    if (!_Py_IsOwnedByCurrentThread(iter_o) && !_PyObject_GC_IS_SHARED(iter_o)) {
         goto failure;
+    }
 #endif
     if (PyStackRef_IsNull(null_or_index)) {
         if (tp == &PyRangeIter_Type) {