Issue #26081: Fix refleak in _asyncio.Future.__iter__().throw.

Misc/NEWS

@@ -38,6 +38,8 @@ Library
 
 - Issue #28634: Fix asyncio.isfuture() to support unittest.Mock.
 
+- Issue #26081: Fix refleak in _asyncio.Future.__iter__().throw.
+
 Documentation
 -------------
 

Modules/_asynciomodule.c

@@ -1044,15 +1044,17 @@ FutureIter_throw(futureiterobject *self, PyObject *args)
     else {
         if (PyExceptionClass_Check(type)) {
             val = PyObject_CallObject(type, NULL);
+            PyErr_SetObject(type, val);
+            Py_DECREF(val);
         }
         else {
             val = type;
             assert (PyExceptionInstance_Check(val));
             type = (PyObject*)Py_TYPE(val);
             assert (PyExceptionClass_Check(type));
-        }
             PyErr_SetObject(type, val);
         }
+    }
     return FutureIter_iternext(self);
 }