[3.7] Fix a compiler warning added in bpo-34872. (GH-9722). (GH-9726)

(cherry picked from commit addf8afb43af58b9bf56a0ecfd0f316dd60ac0c3)
diff --git a/Modules/_asynciomodule.c b/Modules/_asynciomodule.c
index 9f7500a..809879a 100644
--- a/Modules/_asynciomodule.c
+++ b/Modules/_asynciomodule.c
@@ -2663,7 +2663,7 @@
             if (task->task_must_cancel) {
                 PyObject *r;
                 int is_true;
-                r = _PyObject_CallMethodId(fut, &PyId_cancel, NULL);
+                r = _PyObject_CallMethodId(result, &PyId_cancel, NULL);
                 if (r == NULL) {
                     return NULL;
                 }