patch 8.2.3856: Vim9: not enough tests

Problem:    Vim9: not enough tests.
Solution:   Run more expression tests also with Vim9. Fix an uncovered
            problem.

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3856,
 /**/
     3855,
 /**/