Seems this change introduced a compiler warning.

/home/serhiy/py/cpython3.7/Modules/_asynciomodule.c: In function ‘task_step_impl’:
/home/serhiy/py/cpython3.7/Modules/_asynciomodule.c:2666:44: warning: passing argument 1 of ‘_PyObject_CallMethodId’ from incompatible pointer type [-Wincompatible-pointer-types]
                 r = _PyObject_CallMethodId(fut, &PyId_cancel, NULL);
                                            ^~~
In file included from ./Include/Python.h:128:0,
                 from /home/serhiy/py/cpython3.7/Modules/_asynciomodule.c:1:
./Include/abstract.h:315:24: note: expected ‘PyObject * {aka struct _object *}’ but argument is of type ‘FutureObj * {aka struct <anonymous> *}’
 PyAPI_FUNC(PyObject *) _PyObject_CallMethodId(PyObject *obj,
                        ^~~~~~~~~~~~~~~~~~~~~~