patch 7.4.2051

Problem:    No proper testing of trunc_string().
Solution:   Add a unittest for message.c.

src/version.c

@@ -758,6 +758,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2051,
 /**/
     2050,
 /**/