[2017.7] Fixes to scheduler __pub values in kwargs

[garethgreenaway]

Adding a small check to ensure we do not continue to populate kwargs with _pub items from the kwargs item.

What does this PR do?

Causes the scheduler to ignore the kwargs argument when creating the __pub values inside kwargs, otherwise we end with an ever growing dict of nested __pub values.

What issues does this PR fix or reference?

#43386

Tests written?

No

Please review Salt's Contributing Guide for best practices.

[ghost]

@garethgreenaway, thanks for your PR! By analyzing the history of the files in this pull request, we identified @isbm, @vutny and @thatch45 to be potential reviewers.

[cachedout]

Go Go Jenkins!

[rallytime]

@garethgreenaway This is failing because you're using is when you should be using if in your conditional.

[garethgreenaway]

@rallytime 👍 Thanks for catching that. Fixed in last commit.