When calling validate() python function, TypeError exception was thrown
("argument list must be a tuple"), because the call does not have
arguments, and python does not accept empty tuple for execution. NULL
must be used instead, which was handled as argument construction failure
previously.
IO/Group/Policy Python API version is displayed instead of sudo version,
because that is not very meaningful in this context.
They are only displayed in verbose mode.
Example plugins express it more concrete that they are displaying their
version, not the API version.
