fix 'raise type, instance' in Py3 by preventing it from trying to re-instantiate the instance

Cython/Utility/Exceptions.c

@@ -155,7 +155,23 @@ static void __Pyx_Raise(PyObject *type, PyObject *value, PyObject *tb, PyObject
         value = type;
         type = (PyObject*) Py_TYPE(value);
     } else if (PyExceptionClass_Check(type)) {
+        // make sure value is an exception instance of type
+        PyObject *instance_class = NULL;
+        if (value && PyExceptionInstance_Check(value)) {
+            instance_class = (PyObject*) Py_TYPE(value);
+            if (instance_class != type) {
+                if (PyObject_IsSubclass(instance_class, type)) {
+                    // believe the instance
+                    type = instance_class;
+                } else {
+                    instance_class = NULL;
+                }
+            }
+        }
+        if (!instance_class) {
             // instantiate the type now (we don't know when and how it will be caught)
+            // assuming that 'value' is an argument to the type's constructor
+            // not using PyErr_NormalizeException() to avoid ref-counting problems
             PyObject *args;
             if (!value)
                 args = PyTuple_New(0);
@@ -166,7 +182,7 @@ static void __Pyx_Raise(PyObject *type, PyObject *value, PyObject *tb, PyObject
                 args = PyTuple_Pack(1, value);
             if (!args)
                 goto bad;
-        owned_instance = PyEval_CallObject(type, args);
+            owned_instance = PyObject_Call(type, args, NULL);
             Py_DECREF(args);
             if (!owned_instance)
                 goto bad;
@@ -178,6 +194,7 @@ static void __Pyx_Raise(PyObject *type, PyObject *value, PyObject *tb, PyObject
                              type, Py_TYPE(value));
                 goto bad;
             }
+        }
     } else {
         PyErr_SetString(PyExc_TypeError,
             "raise: exception class must be a subclass of BaseException");