patch 7.4.1378
Problem:    Can't change job settings after it started.
Solution:   Add job_setoptions() with the "stoponexit" flag.
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index a052727..61ca9b7 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -44,7 +44,8 @@
 
   try
     if has('job')
-      let s:job = job_start(cmd)
+      let s:job = job_start(cmd, {"stoponexit": "hup"})
+      call job_setoptions(s:job, {"stoponexit": "kill"})
     elseif has('win32')
       exe 'silent !start cmd /c start "test_channel" ' . cmd
     else