Mixed use of .. code:: and ..code-block:: renders some cells as non-execute

[mmcky]

Currently in the test document tests/code-blocks.rst

a mixed use of .. code:: python and .. code-block:: python renders the .. code-block inclusion as a no-exectute cell. This should not be the case as the rest of the document is in python. However inclusion of code-examples for other languages should be no-execute.