closes bpo-37420: Handle errors during iteration in os.sched_setaffinity. (GH-14414)

diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 5f17fce..197607c 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -6413,6 +6413,9 @@
         }
         CPU_SET_S(cpu, setsize, cpu_set);
     }
+    if (PyErr_Occurred()) {
+        goto error;
+    }
     Py_CLEAR(iterator);
 
     if (sched_setaffinity(pid, setsize, cpu_set)) {