updated for version 7.3.831
Problem:    Clumsy to handle the situation that a variable does not exist.
Solution:   Add default value to getbufvar() et al. (Shougo Matsushita,
            Hirohito Higashi)
diff --git a/src/version.c b/src/version.c
index 0881d92..6675d00 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    831,
+/**/
     830,
 /**/
     829,