PL/Python: Remove PLy_result_ass_item

It is apparently no longer used after the new slicing support was
implemented (a97207b6), so let's
remove the dead code and see if anything cares.

src/pl/plpython/plpy_resultobject.c

@@ -21,7 +21,6 @@ static PyObject *PLy_result_status(PyObject *self, PyObject *args);
 static Py_ssize_t PLy_result_length(PyObject *arg);
 static PyObject *PLy_result_item(PyObject *arg, Py_ssize_t idx);
 static PyObject *PLy_result_slice(PyObject *arg, Py_ssize_t lidx, Py_ssize_t hidx);
-static int	PLy_result_ass_item(PyObject *arg, Py_ssize_t idx, PyObject *item);
 static int	PLy_result_ass_slice(PyObject *rg, Py_ssize_t lidx, Py_ssize_t hidx, PyObject *slice);
 static PyObject *PLy_result_subscript(PyObject *arg, PyObject *item);
 static int	PLy_result_ass_subscript(PyObject *self, PyObject *item, PyObject *value);
@@ -36,7 +35,7 @@ static PySequenceMethods PLy_result_as_sequence = {
 	NULL,						/* sq_repeat */
 	PLy_result_item,			/* sq_item */
 	PLy_result_slice,			/* sq_slice */
-	PLy_result_ass_item,		/* sq_ass_item */
+	NULL,						/* sq_ass_item */
 	PLy_result_ass_slice,		/* sq_ass_slice */
 };
 
@@ -231,17 +230,6 @@ PLy_result_item(PyObject *arg, Py_ssize_t idx)
 	return rv;
 }
 
-static int
-PLy_result_ass_item(PyObject *arg, Py_ssize_t idx, PyObject *item)
-{
-	int			rv;
-	PLyResultObject *ob = (PLyResultObject *) arg;
-
-	Py_INCREF(item);
-	rv = PyList_SetItem(ob->rows, idx, item);
-	return rv;
-}
-
 static PyObject *
 PLy_result_slice(PyObject *arg, Py_ssize_t lidx, Py_ssize_t hidx)
 {