patch 7.4.1379
Problem:    Channel test fails on Win32 console.
Solution:   Don't sleep when timeout is zero. Call channel_wait() before
            channel_read(). Channels are not polled during ":sleep". (Yukihiro
            Nakadaira)
diff --git a/src/misc2.c b/src/misc2.c
index 9cfb118..932d67e 100644
--- a/src/misc2.c
+++ b/src/misc2.c
@@ -6239,6 +6239,11 @@
     void
 parse_queued_messages(void)
 {
+    /* For Win32 mch_breakcheck() does not check for input, do it here. */
+# if defined(WIN32) && defined(FEAT_CHANNEL)
+    channel_handle_events();
+# endif
+
 # ifdef FEAT_NETBEANS_INTG
     /* Process the queued netbeans messages. */
     netbeans_parse_messages();