patch 7.4.1380
Problem:    The job exit callback is not implemented.
Solution:   Add the "exit-cb" option.
diff --git a/src/channel.c b/src/channel.c
index d02f019..aa97088 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -833,6 +833,8 @@
 
     call_func(callback, (int)STRLEN(callback),
 			     &rettv, 2, argv, 0L, 0L, &dummy, TRUE, NULL);
+    clear_tv(&rettv);
+
     /* If an echo command was used the cursor needs to be put back where
      * it belongs. */
     setcursor();