the assert usage in the NonNegativeAction has the potential to allow
unexpected behavior when the python is byte-compiled with optimization
turned on.
Changes
* remove assert in favor of if/else in NonNegativeAction class
* add type specifier to parser arguments for non-negative actions
* correct tests for new int based values
Change-Id: I093e7440b8beff4f179e2c4ed81daff82704c40e
Closes-Bug: #1576375