Presently, GApplication considers (for both local and primary command line handling) that a non-zero use count indicates some level of application success and then the application should run and return zero when the main loop quits.  This means that a non-zero status from commandline handlers gets ignored.

Another possibility (and perhaps one that is less confusing) is that we consider a non-zero status from a commandline handler as an indication of complete failure, ignoring the use count of the application.