PyImport_Import does not fall back to default builtins

Bug report

Bug description:

When importing a module with PyImport_Import() inside an already running python which does have limited globals, the import fails due to missing __builtins__: https://github.com/python/cpython/blob/01ba7df49966eaf14f44962a77898840c70dda96/Python/import.c#L3914-L3921

It feels similar to this issue: https://github.com/python/cpython/pull/24564 but with a slightly different setup.

Originally reported for pyo3 here: https://github.com/PyO3/pyo3/issues/4913

Minimal reproducer below, fuller reproducer can be found here: https://gitlab.com/nertpinx/cpython_repr

#include <Python.h>

PyObject *
func(PyObject *self __attribute__((unused)),
     PyObject *arg)
{
    return PyImport_Import(arg);
}

static PyMethodDef method_def = {
    .ml_name = "func",
    .ml_meth = func,
    .ml_flags = METH_NOARGS,
    .ml_doc = "Reproducer function",
};

int
main(int argc __attribute__((unused)),
     char **argv __attribute__((unused)))
{
    Py_InitializeEx(0);

    PyObject *program = NULL;
    PyObject *globals = NULL;
    PyObject *supermodule = NULL;
    PyObject *py_func = NULL;

    supermodule = PyUnicode_FromString("supermodule");
    py_func = PyCFunction_NewEx(&method_def, NULL, supermodule);
    globals = PyDict_New();
    PyDict_SetItemString(globals, "func", py_func);

    program = Py_CompileString("func()", "<string>", Py_file_input);
    PyEval_EvalCode(program, globals, NULL);

    if (PyErr_Occurred()) {
        PyErr_Print();
        return 1;
    }

    return 0;
}

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Comienza en las líneas referenciadas de import.c alrededor de 3914-3921 y crea el reproductor mínimo en C contra CPython 3.13. Comprueba cómo PyImport_Import gestiona los globals sin builtins y añade una prueba de regresión que cubra la configuración de globals limitados. Se considera terminado cuando la importación tiene éxito usando los builtins predeterminados en lugar de fallar por la ausencia de builtins.