updated for version 7.3.891

Problem:    Merging viminfo history doesn't work well.
Solution:   Don't stop when one type of history is empty. Don't merge history
            when writing viminfo.

src/version.c

@@ -728,6 +728,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    891,
 /**/
     890,
 /**/