patch 7.4.1413
Problem:    When calling ch_close() the close callback is invoked, even though
            the docs say it isn't. (Christian J. Robinson)
Solution:   Don't call the close callback.
diff --git a/src/proto/channel.pro b/src/proto/channel.pro
index 81935bf..96b51b9 100644
--- a/src/proto/channel.pro
+++ b/src/proto/channel.pro
@@ -17,7 +17,7 @@
 int channel_can_write_to(channel_T *channel);
 int channel_is_open(channel_T *channel);
 char *channel_status(channel_T *channel);
-void channel_close(channel_T *channel);
+void channel_close(channel_T *channel, int invoke_close_cb);
 char_u *channel_peek(channel_T *channel, int part);
 void channel_clear(channel_T *channel);
 void channel_free_all(void);