MDEV-29880 Galera test failure on GCF-336

Fix `wsrep_table_accessible_when_detached()` so that commands that
access no tables are rejected while a node is disconnected from a
cluster.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>

mysql-test/suite/galera/r/galera_var_dirty_reads.result

@@ -19,9 +19,9 @@ SHOW STATUS LIKE 'wsrep_cluster_status';
 Variable_name	Value
 wsrep_cluster_status	Disconnected
 SELECT * FROM t1;
-Got one of the listed errors
+ERROR 08S01: WSREP has not yet prepared node for application use
 SELECT 1 FROM t1;
-Got one of the listed errors
+ERROR 08S01: WSREP has not yet prepared node for application use
 SET @@session.wsrep_dirty_reads=ON;
 SELECT * FROM t1;
 i
@@ -34,7 +34,7 @@ i	variable_name	variable_value
 1	WSREP_DIRTY_READS	ON
 SET @@session.wsrep_dirty_reads=OFF;
 SELECT i, variable_name, variable_value FROM t1, information_schema.session_variables WHERE variable_name LIKE "wsrep_dirty_reads" AND i = 1;
-Got one of the listed errors
+ERROR 08S01: WSREP has not yet prepared node for application use
 SELECT 1;
 1
 1

mysql-test/suite/galera/t/galera_var_dirty_reads.test

@@ -31,10 +31,10 @@ SHOW STATUS LIKE 'wsrep_ready';
 # Must return 'Disconnected'
 SHOW STATUS LIKE 'wsrep_cluster_status';
 
---error ER_UNKNOWN_COM_ERROR,1047
+--error ER_UNKNOWN_COM_ERROR
 SELECT * FROM t1;
 
---error ER_UNKNOWN_COM_ERROR,1047
+--error ER_UNKNOWN_COM_ERROR
 SELECT 1 FROM t1;
 
 SET @@session.wsrep_dirty_reads=ON;
@@ -46,7 +46,7 @@ SELECT i, variable_name, variable_value FROM t1, information_schema.session_vari
 
 SET @@session.wsrep_dirty_reads=OFF;
 
---error ER_UNKNOWN_COM_ERROR,1047
+--error ER_UNKNOWN_COM_ERROR
 SELECT i, variable_name, variable_value FROM t1, information_schema.session_variables WHERE variable_name LIKE "wsrep_dirty_reads" AND i = 1;
 
 

mysql-test/suite/galera_3nodes_sr/disabled.def

-GCF-336 : 
 GCF-582 : 
 GCF-810A : 
 GCF-810B : 

mysql-test/suite/galera_3nodes_sr/r/GCF-336.result

+connection node_2;
+connection node_1;
+connection node_2;
 CREATE TABLE t1 (f1 INTEGER) ENGINE=InnoDB;
 SET SESSION wsrep_trx_fragment_size = 1;
 SET AUTOCOMMIT=OFF;
 START TRANSACTION;
 INSERT INTO t1 VALUES (1);
+connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2;
+connection node_2a;
 SELECT COUNT(*) > 0 FROM mysql.wsrep_streaming_log;
 COUNT(*) > 0
 1
+connection node_1;
 SELECT COUNT(*) > 0 FROM mysql.wsrep_streaming_log;
 COUNT(*) > 0
 1
@@ -13,14 +19,19 @@ SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
 SELECT COUNT(*) > 0 FROM t1;
 COUNT(*) > 0
 1
+connection node_2a;
 SET GLOBAL wsrep_provider_options = 'gmcast.isolate=1';
 SET SESSION wsrep_sync_wait=0;
+connection node_2;
 INSERT INTO t1 VALUES (2);
 ERROR 40001: Deadlock found when trying to get lock; try restarting transaction
 COMMIT;
 ERROR 08S01: WSREP has not yet prepared node for application use
+connection node_2a;
 SET GLOBAL wsrep_provider_options = 'gmcast.isolate=0';
 DROP TABLE t1;
 CALL mtr.add_suppression("replication aborted");
 CALL mtr.add_suppression("WSREP: fragment replication failed: 3");
 CALL mtr.add_suppression("WSREP: failed to send SR rollback for ");
+connect node_3, 127.0.0.1, root, , test, $NODE_MYPORT_3;
+connection node_3;

sql/sql_parse.cc

@@ -1162,7 +1162,7 @@ static bool wsrep_tables_accessible_when_detached(const TABLE_LIST *tables)
     if (get_table_category(&db, &tn)  < TABLE_CATEGORY_INFORMATION)
       return false;
   }
-  return true;
+  return tables != NULL;
 }
 
 static bool wsrep_command_no_result(char command)
@@ -3716,6 +3716,8 @@ mysql_execute_command(THD *thd)
           (sql_command_flags[lex->sql_command] & CF_CHANGES_DATA) == 0)    &&
         !wsrep_tables_accessible_when_detached(all_tables)                 &&
         lex->sql_command != SQLCOM_SET_OPTION                              &&
+        lex->sql_command != SQLCOM_CHANGE_DB                               &&
+        !(lex->sql_command == SQLCOM_SELECT && !all_tables)                &&
         !wsrep_is_show_query(lex->sql_command))
     {
       my_message(ER_UNKNOWN_COM_ERROR,