Comment 3 for bug 1555764

@Alexander- Thanks for the feedback.
Kindly refer to https://review.openstack.org/#/c/293569/3/tests/unit/cli/test_cliutils.py and consider the new test case that I have added which covers the case discussed in the bug.

>>> from rally.cli.cliutils import validate_args
>>> validate_args(lambda x,y:None,1,x=1)
>>>
lambda x,y:None has 2 required args- x and y
The above case should have thrown an error saying Missing arguments: y. But with current code base it does NOT throw an error for missing argument "y"