patch 8.2.3867: implementation of some list functions too complicated

Problem:    Implementation of some list functions too complicated.
Solution:   Refactor do_sort_uniq(), f_count() and extend() (Yegappan
            Lakshmanan, closes #9378)

src/version.c

@@ -749,6 +749,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3867,
 /**/
     3866,
 /**/