IndexError on Matmul

[disktnk]

When put vector parameters, matmul converter occurs an error.

    @support((1, 6, 7))
    def convert_MatMul(func, opset_version, input_names,
                       output_names, context, parameters):
        bias_shape = (
>           func.inputs[0].shape[-1] if func.transa else func.inputs[0].shape[-2],
            func.inputs[1].shape[-2] if func.transb else func.inputs[1].shape[-1]
        )
E       IndexError: Parameterized test failed.
E
E       Base test method: TestBinaryMathOperators.test_vector
E       Test parameters:
E         op_name: MatMul
E         ops: chainer.functions.matmul(a, b, transb=True)
E
E
E       (caused by)
E       IndexError: tuple index out of range