MDEV-13711 Assertion failure on CREATE TABLE .. LIKE <sequence>

Fixes two issues:
- Update assert in open_and_process_tables to handle sequences
- Removed not needed and conflicting mdl_context.release_transactional_locks
  in sql_sequence.cc. The MDL lock is released at end of
  mysql_execute_command().

Signed-off-by: Monty <monty@mariadb.org>

mysql-test/suite/sql_sequence/create.result

@@ -499,6 +499,27 @@ drop sequence t1;
 create table t1 (a int) engine=sql_sequence;
 ERROR 42000: Unknown storage engine 'sql_sequence'
 #
+# MDEV-13711 assertion on CREATE LIKE fix
+#
+create sequence s;
+create table t like s;
+show create table t;
+Table	Create Table
+t	CREATE TABLE `t` (
+  `next_not_cached_value` bigint(21) NOT NULL,
+  `minimum_value` bigint(21) NOT NULL,
+  `maximum_value` bigint(21) NOT NULL,
+  `start_value` bigint(21) NOT NULL COMMENT 'start value when sequences is created or value if RESTART is used',
+  `increment` bigint(21) NOT NULL COMMENT 'increment value',
+  `cache_size` bigint(21) unsigned NOT NULL,
+  `cycle_option` tinyint(1) unsigned NOT NULL COMMENT '0 if no cycles are allowed, 1 if the sequence should begin a new cycle when maximum_value is passed',
+  `cycle_count` bigint(21) NOT NULL COMMENT 'How many cycles have been done'
+) ENGINE=MyISAM SEQUENCE=1
+show create sequence t;
+Table	Create Table
+t	CREATE SEQUENCE `t` start with 1 minvalue 1 maxvalue 9223372036854775806 increment by 1 cache 1000 nocycle ENGINE=MyISAM
+drop tables t, s;
+#
 # MDEV-13714 SEQUENCE option fix
 #
 create or replace table s (

mysql-test/suite/sql_sequence/create.test

@@ -376,6 +376,16 @@ drop sequence t1;
 --error ER_UNKNOWN_STORAGE_ENGINE
 create table t1 (a int) engine=sql_sequence;
 
+--echo #
+--echo # MDEV-13711 assertion on CREATE LIKE fix
+--echo #
+
+create sequence s;
+create table t like s;
+show create table t;
+show create sequence t;
+drop tables t, s;
+
 --echo #
 --echo # MDEV-13714 SEQUENCE option fix
 --echo #

sql/sql_base.cc

@@ -3338,9 +3338,9 @@ open_and_process_table(THD *thd, LEX *lex, TABLE_LIST *tables,
     /*
       If this TABLE_LIST object has an associated open TABLE object
       (TABLE_LIST::table is not NULL), that TABLE object must be a pre-opened
-      temporary table.
+      temporary table or SEQUENCE (see sequence_insert()).
     */
-    DBUG_ASSERT(is_temporary_table(tables));
+    DBUG_ASSERT(is_temporary_table(tables) || tables->table->s->sequence);
   }
   else if (tables->open_type == OT_TEMPORARY_ONLY)
   {

sql/sql_sequence.cc

@@ -334,7 +334,6 @@ bool sequence_insert(THD *thd, LEX *lex, TABLE_LIST *table_list)
   trans_commit_implicit(thd);
   if (!temporary_table)
     close_thread_tables(thd);
-  thd->mdl_context.release_transactional_locks();
   DBUG_RETURN(error);
 }