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Cython/Utility/ObjectHandling.c

@@ -1946,6 +1946,7 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_FastCall(PyObject *func, PyObject
         return f(func, args, nargs, NULL);
     }
     #elif __Pyx_CyFunction_USED && CYTHON_BACKPORT_VECTORCALL
+    // exclude fused functions for now
     if (Py_TYPE(func) == __pyx_CyFunctionType) {
         __pyx_vectorcallfunc f = __Pyx_CyFunction_func_vectorcall(func);
         if (f) return f(func, args, nargs, NULL);