updated for version 7.3.851
Problem:    Using an empty pattern with :sort silently continues when there is
            no previous search pattern.
Solution:   Give an error message.
diff --git a/src/version.c b/src/version.c
index b4234e0..97fdd99 100644
--- a/src/version.c
+++ b/src/version.c
@@ -729,6 +729,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    851,
+/**/
     850,
 /**/
     849,