Do not intercept our own tp_init function (pybind11_object_init).

include/pybind11/detail/class.h

@@ -407,7 +407,7 @@ extern "C" int pybind11_object_init(PyObject *self, PyObject *, PyObject *);
 /// Instance creation function for all pybind11 types. It only allocates space for the
 /// C++ object, but doesn't call the constructor -- an `__init__` function must do that.
 extern "C" inline PyObject *pybind11_object_new(PyTypeObject *type, PyObject *, PyObject *) {
-    if (type->tp_init != tp_init_intercepted) {
+    if (type->tp_init != tp_init_intercepted && type->tp_init != pybind11_object_init) {
         (*derived_tp_init_registry())[type] = type->tp_init;
         type->tp_init = tp_init_intercepted;
     }