patch 7.4.1662
Problem:    No test for an invalid Ex command on a channel.
Solution:   Test handling an invalid command gracefully.  Avoid getting an
            error message, do write it to the channel log.
diff --git a/src/channel.c b/src/channel.c
index 64393f9..22f63b3 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -1661,8 +1661,17 @@
 
     if (STRCMP(cmd, "ex") == 0)
     {
+	int save_called_emsg = called_emsg;
+
+	called_emsg = FALSE;
 	ch_logs(channel, "Executing ex command '%s'", (char *)arg);
+	++emsg_silent;
 	do_cmdline_cmd(arg);
+	--emsg_silent;
+	if (called_emsg)
+	    ch_logs(channel, "Ex command error: '%s'",
+					  (char *)get_vim_var_str(VV_ERRMSG));
+	called_emsg = save_called_emsg;
     }
     else if (STRCMP(cmd, "normal") == 0)
     {
diff --git a/src/testdir/test_channel.py b/src/testdir/test_channel.py
index 227780a..b5a912c 100644
--- a/src/testdir/test_channel.py
+++ b/src/testdir/test_channel.py
@@ -73,6 +73,11 @@
                         print("sending: {0}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
+                    elif decoded[1] == 'bad command':
+                        cmd = '["ex","foo bar"]'
+                        print("sending: {0}".format(cmd))
+                        self.request.sendall(cmd.encode('utf-8'))
+                        response = "ok"
                     elif decoded[1] == 'do normal':
                         # Send a normal command.
                         cmd = '["normal","G$s more\u001b"]'
diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index b356c88..7051223 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -151,6 +151,11 @@
   call assert_equal('added1', getline(line('$') - 1))
   call assert_equal('added2', getline('$'))
 
+  " Request command "foo bar", which fails silently.
+  call assert_equal('ok', ch_evalexpr(handle, 'bad command'))
+  call s:waitFor('v:errmsg =~ "E492"')
+  call assert_true(v:errmsg =~ 'E492:.*foo bar')
+
   call assert_equal('ok', ch_evalexpr(handle, 'do normal', {'timeout': 100}))
   call s:waitFor('"added more" == getline("$")')
   call assert_equal('added more', getline('$'))
diff --git a/src/version.c b/src/version.c
index 7e63f1f..b19190d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -749,6 +749,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1662,
+/**/
     1661,
 /**/
     1660,