patch 7.4.1989
Problem:    filter() and map() only accept a string argument.
Solution:   Implement using a Funcref argument (Yasuhiro Matsumoto, Ken
            Takata)
diff --git a/src/version.c b/src/version.c
index a89b83e..7588c9c 100644
--- a/src/version.c
+++ b/src/version.c
@@ -759,6 +759,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1989,
+/**/
     1988,
 /**/
     1987,