crash and burn during "pkg test pythonic"

See https://savannah.gnu.org/bugs/?66820 for details. Doing pkg test pythonic crashes with assertion failure. The patch:

 diff --git a/src/Makefile b/src/Makefile
index fbc5c1f..c0a7a22 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -30,7 +30,6 @@ SED             ?= sed

 ARFLAGS  = cr

-export CXXFLAGS ?= -g -O2

 srcdir = .

diff --git a/src/oct-py-types.cc b/src/oct-py-types.cc
index a863344..831a6bb 100644
--- a/src/oct-py-types.cc
+++ b/src/oct-py-types.cc
@@ -407,8 +407,21 @@ namespace pythonic
     if (PyLong_Check (obj))
       {
         // FIXME: if (value < 0), may be very implementation dependent
-        if (Py_SIZE (obj) < 0)
+        // if (Py_SIZE (obj) < 0)
+
+        // Check if the number is negative
+        // In Python 3.13+, we can't use Py_SIZE on PyLong objects
+        // Instead, check if the number is negative by comparing with zero
+        // using a public API
+        int is_negative = PyObject_RichCompareBool(obj, PyLong_FromLong(0), Py_LT);
+        if (is_negative == 1)
           return 0;
+        else if (is_negative == -1)
+          // If the comparison fails for some reason (returns -1),
+          // just call PyErr_Clear() to clear that exception and allow
+          // the code to continue execution.
+          // Is there a better way to handle it?
+          PyErr_Clear();

 #if (defined (HAVE_LONG_LONG) && (SIZEOF_LONG_LONG == 8))
         unsigned PY_LONG_LONG value = PyLong_AsUnsignedLongLong (obj);

(also attached) fixes that for me. But I do not really know the code so it could be wrong. das_pythonic.diff.gz

Dmitri.