Amend modelSort functions in test_behind_idioms

[bear8642]

The modelSort functions in tests/behind.apln: test_behind_idioms are optimised idioms that call the same underlying code as the sort functions.

Given that they are supposed to be models, should the modelSort functions be changed to not use an optimised idiom?

[sloorush]

Thanks for reporting!

The model function should definitely be changed if it triggers the same idioms. I was under the impression that writing the model function in this form does not trigger the underlying idiom.