patch 7.4.1303
Problem:    A Funcref is not accepted as a callback.
Solution:   Make a Funcref work. (Damien)
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index 6e5bbbb..9f52eb7 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -118,6 +118,13 @@
   call assert_equal(handle, s:responseHandle)
   call assert_equal('got it', s:responseMsg)
 
+  let s:responseHandle = -1
+  let s:responseMsg = ''
+  call ch_sendexpr(handle, 'hello!', function('s:RequestHandler'))
+  sleep 10m
+  call assert_equal(handle, s:responseHandle)
+  call assert_equal('got it', s:responseMsg)
+
   " Send an eval request that works.
   call assert_equal('ok', ch_sendexpr(handle, 'eval-works'))
   sleep 10m
@@ -206,13 +213,12 @@
 
 let s:reply = ""
 func s:Handler(chan, msg)
+  unlet s:reply
   let s:reply = a:msg
 endfunc
 
 func s:channel_handler(port)
-  let chopt = copy(s:chopt)
-  let chopt['callback'] = 's:Handler'
-  let handle = ch_open('localhost:' . a:port, chopt)
+  let handle = ch_open('localhost:' . a:port, s:chopt)
   if handle < 0
     call assert_false(1, "Can't open channel")
     return
@@ -230,7 +236,11 @@
 endfunc
 
 func Test_channel_handler()
+  let s:chopt.callback = 's:Handler'
   call s:run_server('s:channel_handler')
+  let s:chopt.callback = function('s:Handler')
+  call s:run_server('s:channel_handler')
+  unlet s:chopt.callback
 endfunc
 
 " Test that trying to connect to a non-existing port fails quickly.