patch 7.4.1318
Problem:    Channel with pipes doesn't work in GUI.
Solution:   Register input handlers for pipes.
diff --git a/src/eval.c b/src/eval.c
index 75f5e54..a36f3dd 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -9970,12 +9970,12 @@
     channel = channel_open((char *)address, port, waittime, NULL);
     if (channel != NULL)
     {
+	rettv->vval.v_channel = channel;
 	channel_set_json_mode(channel, ch_mode);
 	channel_set_timeout(channel, timeout);
 	if (callback != NULL && *callback != NUL)
 	    channel_set_callback(channel, callback);
     }
-    rettv->vval.v_channel = channel;
 }
 
 /*