patch 8.2.0921: CTRL-W T in cmdline window causes trouble

Problem:    CTRL-W T in cmdline window causes trouble.
Solution:   Disallow CTRL-W T in the cmdline window.  Add more tests.
            (Naruhiko Nishino, closes #6219)
diff --git a/src/version.c b/src/version.c
index c400df4..ec6117f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    921,
+/**/
     920,
 /**/
     919,