patch 8.0.1429: crash when calling term_start() with empty argument

Problem:    Crash when calling term_start() with empty argument.
Solution:   Check for invalid argument. (Yasuhiro Matsomoto, closes #2503)
            Fix memory leak.

src/version.c

@@ -771,6 +771,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1429,
 /**/
     1428,
 /**/