Make sure there is always a 'return' in the specialised set iteration C code, also in non-CPython.
Make sure there is always a 'return' in the specialised set iteration C code, also in non-CPython.

scoder/cython,da-woods/cython,cython/cython,da-woods/cython,scoder/cython,cython/cython,scoder/cython,scoder/cython,da-woods/cython,cython/cython,da-woods/cython,cython/cython