Merge pull request #11216 from dan-masek:fix_issue_11205

modules/python/src2/cv2.cpp

@@ -1636,6 +1636,8 @@ static void OnChange(int pos, void *param)
     PyObject *r = PyObject_Call(PyTuple_GetItem(o, 0), args, NULL);
     if (r == NULL)
         PyErr_Print();
+    else
+        Py_DECREF(r);
     Py_DECREF(args);
     PyGILState_Release(gstate);
 }
@@ -1678,6 +1680,8 @@ static void OnButtonChange(int state, void *param)
     PyObject *r = PyObject_Call(PyTuple_GetItem(o, 0), args, NULL);
     if (r == NULL)
         PyErr_Print();
+    else
+        Py_DECREF(r);
     Py_DECREF(args);
     PyGILState_Release(gstate);
 }