Add test case for unsafe-unbox and box-cas!
Add test case for unsafe-unbox and box-cas!

magnusmorton/pycket,cderici/pycket,samth/pycket,cderici/pycket,pycket/pycket,cderici/pycket,pycket/pycket,samth/pycket,magnusmorton/pycket,pycket/pycket,magnusmorton/pycket,samth/pycket