MDEV-18713 Assertion `strcmp(share->unique_file_name,filename) ||...

MDEV-18713 Assertion `strcmp(share->unique_file_name,filename) || share->last_version' failed in test_if_reopen upon REPLACE into table with key on blob

close table->update_handler in close_thread_tables().
it's not enough to do it in sql_update.cc only, because
sql_insert.cc can also do updates (REPLACE) and even
sql_delete.cc can (DELETE ... FOR PORTION OF)

mysql-test/main/long_unique_bugs.result

@@ -20,3 +20,9 @@ t1	CREATE TABLE `t1` (
   UNIQUE KEY `b` (`b`) USING HASH
 ) ENGINE=InnoDB DEFAULT CHARSET=latin1
 drop table t1;
+create table t1 (pk int, b blob, primary key(pk), unique(b)) engine=myisam;
+insert into t1 values (1,'foo');
+replace into t1 (pk) values (1);
+alter table t1 force;
+replace into t1 (pk) values (1);
+drop table t1;

mysql-test/main/long_unique_bugs.test

@@ -26,3 +26,13 @@ alter table t1 add unique (b);
 alter table t1 force;
 show create table t1;
 drop table t1;
+
+#
+# MDEV-18713 Assertion `strcmp(share->unique_file_name,filename) || share->last_version' failed in test_if_reopen upon REPLACE into table with key on blob
+#
+create table t1 (pk int, b blob, primary key(pk), unique(b)) engine=myisam;
+insert into t1 values (1,'foo');
+replace into t1 (pk) values (1);
+alter table t1 force;
+replace into t1 (pk) values (1);
+drop table t1;

sql/sql_base.cc

@@ -850,12 +850,16 @@ void close_thread_tables(THD *thd)
   DBUG_ASSERT(thd->transaction.stmt.is_empty() || thd->in_sub_stmt ||
               (thd->state_flags & Open_tables_state::BACKUPS_AVAIL));
 
-  /* Detach MERGE children after every statement. Even under LOCK TABLES. */
   for (table= thd->open_tables; table; table= table->next)
   {
+    if (table->update_handler)
+      table->delete_update_handler();
+
     /* Table might be in use by some outer statement. */
     DBUG_PRINT("tcache", ("table: '%s'  query_id: %lu",
                           table->s->table_name.str, (ulong) table->query_id));
+
+    /* Detach MERGE children after every statement. Even under LOCK TABLES. */
     if (thd->locked_tables_mode <= LTM_LOCK_TABLES ||
         table->query_id == thd->query_id)
     {

sql/sql_update.cc

@@ -1137,8 +1137,6 @@ int mysql_update(THD *thd,
       break;
     }
   }
-  if (table->update_handler)
-    table->delete_update_handler();
   ANALYZE_STOP_TRACKING(&explain->command_tracker);
   table->auto_increment_field_not_null= FALSE;
   dup_key_found= 0;
@@ -2371,8 +2369,6 @@ multi_update::~multi_update()
   for (table= update_tables ; table; table= table->next_local)
   {
     table->table->no_keyread= 0;
-    if (table->table->update_handler)
-      table->table->delete_update_handler();
     if (ignore)
       table->table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);
   }