patch 7.4.1336
Problem:    Channel NL mode is not supported yet.
Solution:   Add NL mode support to channels.
diff --git a/src/testdir/test_channel_pipe.py b/src/testdir/test_channel_pipe.py
index 495fa80..5994d27 100644
--- a/src/testdir/test_channel_pipe.py
+++ b/src/testdir/test_channel_pipe.py
@@ -21,4 +21,7 @@
         if typed.startswith("echo"):
             print(typed[5:-1])
             sys.stdout.flush()
+        if typed.startswith("double"):
+            print(typed[7:-1] + "\nAND " + typed[7:-1])
+            sys.stdout.flush()