patch 7.4.2251
Problem:    In rare cases diffing 4 buffers is not enough.
Solution:   Raise the limit to 8. (closes #1000)
diff --git a/src/structs.h b/src/structs.h
index 1dfe131..e559220 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -2296,7 +2296,7 @@
 /*
  * Stuff for diff mode.
  */
-# define DB_COUNT 4	/* up to four buffers can be diff'ed */
+# define DB_COUNT 8	/* up to eight buffers can be diff'ed */
 
 /*
  * Each diffblock defines where a block of lines starts in each of the buffers