updated for version 7.3.407
Problem:    ":12verbose call F()" may duplicate text while trying to truncate.
            (Thinca)
Solution:   Only truncate when there is not enough room.  Also check the byte
            length of the buffer.
diff --git a/src/buffer.c b/src/buffer.c
index 2884b30..8cf5f8a 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -3258,9 +3258,8 @@
 	    if (maxlen > 0)
 	    {
 		/* make it shorter by removing a bit in the middle */
-		len = vim_strsize(buf);
-		if (len > maxlen)
-		    trunc_string(buf, buf, maxlen);
+		if (vim_strsize(buf) > maxlen)
+		    trunc_string(buf, buf, maxlen, IOSIZE);
 	    }
 	}
     }