MDEV-18820 Assertion `lock_table_has(trx, index->table, LOCK_IX)' failed in...

MDEV-18820 Assertion `lock_table_has(trx, index->table, LOCK_IX)' failed in lock_rec_insert_check_and_lock upon INSERT into table with blob key

Don't Ignore Any error during index lookup, And throw duplicate key error
only if error is HA_ERR_FOUND_DUPP_KEY

mysql-test/main/long_unique_bugs.result

@@ -239,3 +239,29 @@ CREATE TABLE t1 (a INT, UNIQUE USING HASH (a)) PARTITION BY HASH (a) PARTITIONS
 INSERT INTO t1 VALUES (2);
 REPLACE INTO t1 VALUES (2);
 DROP TABLE t1;
+set innodb_lock_wait_timeout= 10;
+CREATE TABLE t1 (
+id int primary key,
+f INT unique
+) ENGINE=InnoDB;
+CREATE TABLE t2 (
+id int primary key,
+a blob unique
+) ENGINE=InnoDB;
+START TRANSACTION;
+connect  con1,localhost,root,,test;
+connection con1;
+set innodb_lock_wait_timeout= 10;
+START TRANSACTION;
+INSERT INTO t1  VALUES (1,1)/*1*/;
+connection default;
+INSERT INTO t2 VALUES (2, 1)/*2*/ ;
+connection con1;
+INSERT INTO t2 VALUES (3, 1)/*3*/;
+connection default;
+INSERT IGNORE INTO t1 VALUES (4, 1)/*4*/;
+connection con1;
+ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
+disconnect con1;
+connection default;
+DROP TABLE t1, t2;

mysql-test/main/long_unique_bugs.test

 --source include/have_innodb.inc
+--source include/have_partition.inc
 
 #
 # MDEV-18707 Server crash in my_hash_sort_bin, ASAN heap-use-after-free in Field::is_null, server hang, corrupted double-linked list
@@ -269,8 +270,50 @@ drop table t1;
 #
 # MDEV-18904 Assertion `m_part_spec.start_part >= m_part_spec.end_part' failed in ha_partition::index_read_idx_map
 #
---source include/have_partition.inc
 CREATE TABLE t1 (a INT, UNIQUE USING HASH (a)) PARTITION BY HASH (a) PARTITIONS 2;
 INSERT INTO t1 VALUES (2);
 REPLACE INTO t1 VALUES (2);
 DROP TABLE t1;
+
+#
+# MDEV-18820 Assertion `lock_table_has(trx, index->table, LOCK_IX)' failed in lock_rec_insert_check_and_lock upon INSERT into table with blob key'
+#
+
+--source include/have_innodb.inc
+set innodb_lock_wait_timeout= 10;
+
+CREATE TABLE t1 (
+  id int primary key,
+  f INT unique
+) ENGINE=InnoDB;
+
+CREATE TABLE t2 (
+  id int primary key,
+  a blob unique
+) ENGINE=InnoDB;
+
+START TRANSACTION;
+
+--connect (con1,localhost,root,,test)
+
+--connection con1
+set innodb_lock_wait_timeout= 10;
+START TRANSACTION;
+INSERT INTO t1  VALUES (1,1)/*1*/;
+
+--connection default
+INSERT INTO t2 VALUES (2, 1)/*2*/ ;
+
+--connection con1
+--send
+  INSERT INTO t2 VALUES (3, 1)/*3*/;
+
+--connection default
+INSERT IGNORE INTO t1 VALUES (4, 1)/*4*/;
+
+--connection con1
+--error ER_LOCK_DEADLOCK
+--reap
+--disconnect con1
+--connection default
+DROP TABLE t1, t2;

sql/handler.cc

@@ -6590,10 +6590,10 @@ static int check_duplicate_long_entry_key(TABLE *table, handler *h,
       error= HA_ERR_FOUND_DUPP_KEY;
     goto exit;
   }
-  if (result == HA_ERR_LOCK_WAIT_TIMEOUT)
-    error= HA_ERR_LOCK_WAIT_TIMEOUT;
+  if (result != HA_ERR_KEY_NOT_FOUND)
+    error= result;
 exit:
-  if (error)
+  if (error == HA_ERR_FOUND_DUPP_KEY)
   {
     table->file->errkey= key_no;
     if (h->ha_table_flags() & HA_DUPLICATE_POS)