Fixup comment

Author: colesbury

Modules/_testcapi/object.c

@@ -168,7 +168,9 @@ test_py_try_inc_ref(PyObject *self, PyObject *unused)
 
     PyUnstable_EnableTryIncRef(op);
 #ifdef Py_GIL_DISABLED
-    // PyUnstable_EnableTryIncRef sets the shared flags to *at least*
+    // PyUnstable_EnableTryIncRef sets the shared flags to
+    // `_Py_REF_MAYBE_WEAKREF` if the flags are currently zero to ensure that
+    // the shared reference count is merged on deallocation.
     assert((op->ob_ref_shared & _Py_REF_SHARED_FLAG_MASK) >= _Py_REF_MAYBE_WEAKREF);
 #endif