Fix for BUG#13814: in mi_pack_key(), when processing NULL value for TINYBLOB key segment,

do advance the source pointer over 2 bytes that specify value length.

myisam/mi_key.c

@@ -217,7 +217,10 @@ uint _mi_pack_key(register MI_INFO *info, uint keynr, uchar *key, uchar *old,
       {
 	k_length-=length;
         if (keyseg->flag & (HA_VAR_LENGTH | HA_BLOB_PART))
+        {
+          old+= 2;
           k_length-=2;                                  /* Skip length */
+        }
 	continue;					/* Found NULL */
       }
     }

mysql-test/r/myisam.result

@@ -702,3 +702,21 @@ t1	1	a	2	b	A	0	NULL	NULL	YES	BTREE
 t1	1	a	3	c	A	0	NULL	NULL	YES	BTREE	
 t1	1	a	4	d	A	0	NULL	NULL	YES	BTREE	
 set myisam_stats_method=DEFAULT;
+drop table t1;
+create table t1(
+cip INT NOT NULL,
+time TIME NOT NULL,
+score INT NOT NULL DEFAULT 0,
+bob TINYBLOB
+);
+insert into t1 (cip, time) VALUES (1, '00:01'), (2, '00:02'), (3,'00:03');
+insert into t1 (cip, bob, time) VALUES (4, 'a', '00:04'), (5, 'b', '00:05'), 
+(6, 'c', '00:06');
+select * from t1 where bob is null and cip=1;
+cip	time	score	bob
+1	00:01:00	0	NULL
+create index bug on t1 (bob(22), cip, time);
+select * from t1 where bob is null and cip=1;
+cip	time	score	bob
+1	00:01:00	0	NULL
+drop table t1;

mysql-test/t/myisam.test

@@ -656,4 +656,22 @@ analyze table t1;
 show index from t1;
 
 set myisam_stats_method=DEFAULT;
+drop table t1;
+
+# BUG#13814 - key value packed incorrectly for TINYBLOBs
+
+create table t1(
+  cip INT NOT NULL,
+  time TIME NOT NULL,
+  score INT NOT NULL DEFAULT 0,
+  bob TINYBLOB
+);
+
+insert into t1 (cip, time) VALUES (1, '00:01'), (2, '00:02'), (3,'00:03');
+insert into t1 (cip, bob, time) VALUES (4, 'a', '00:04'), (5, 'b', '00:05'), 
+                                       (6, 'c', '00:06');
+select * from t1 where bob is null and cip=1;
+create index bug on t1 (bob(22), cip, time);
+select * from t1 where bob is null and cip=1;
+drop table t1;
 # End of 4.1 tests