update async iter tests to match Py3.5.2+ interface
update async iter tests to match Py3.5.2+ interface

c-blake/cython,fabianrost84/cython,scoder/cython,scoder/cython,cython/cython,cython/cython,scoder/cython,fabianrost84/cython,ChristopherHogan/cython,fabianrost84/cython,cython/cython,da-woods/cython,ChristopherHogan/cython,c-blake/cython,da-woods/cython,scoder/cython,da-woods/cython,da-woods/cython,fabianrost84/cython,fabianrost84/cython,cython/cython,c-blake/cython,c-blake/cython,c-blake/cython,ChristopherHogan/cython