patch 7.4.1859
Problem:    Cannot use a function reference for "exit_cb".
Solution:   Use get_callback(). (Yegappan Lakshmanan)
diff --git a/src/version.c b/src/version.c
index 85f57e5..eb9f2c7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1859,
+/**/
     1858,
 /**/
     1857,