Fix test_grow_error()

Author: vstinner

Objects/bytesobject.c

@@ -3696,6 +3696,10 @@ byteswriter_resize(PyBytesWriter *writer, Py_ssize_t size, int resize)
     if (writer->obj != NULL) {
         if (writer->use_bytearray) {
             if (PyByteArray_Resize(writer->obj, size)) {
+#ifdef Py_DEBUG
+                // bytearray can override the canary byte on error
+                byteswriter_write_canary_byte(writer);
+#endif
                 return -1;
             }
         }