updated for version 7.3.689
Problem:    MzScheme and Lua may use a NULL string.
Solution:   Use an empty string instead of NULL. (Yukihiro Nakadaira)
diff --git a/src/version.c b/src/version.c
index d512955..0ea098b 100644
--- a/src/version.c
+++ b/src/version.c
@@ -720,6 +720,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    689,
+/**/
     688,
 /**/
     687,