patch 7.4.2120
Problem:    User defined functions can't be a closure.
Solution:   Add the "closure" argument. Allow using :unlet on a bound
            variable. (Yasuhiro Matsumoto, Ken Takata)
diff --git a/src/version.c b/src/version.c
index 865ac92..7e8ca16 100644
--- a/src/version.c
+++ b/src/version.c
@@ -759,6 +759,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2120,
+/**/
     2119,
 /**/
     2118,