MDEV-13549 Fix and re-enable MTR test galera.MW-284

The following changes are committed:

* `RESET MASTER` at the end of the test. This was necessary to allow the test
  to run on repeated runs.

* `--source include/galera_wait_ready.inc` after setting `gmcast.isolate=0` to
  get back to a primary component.

* Fix for assertion in `Protocol::end_statement()`. The assertion is due to
  the fact that function `do_command()` calls `thd->protocol->end_statement()`,
  without setting an error, when it is detected that galera is not ready yet.
  Following line somehow disappeared in a past merge:
  ```
  my_message(ER_UNKNOWN_COM_ERROR,
             "WSREP has not yet prepared node for application use", MYF(0));
  ```

mysql-test/suite/galera/disabled.def

@@ -40,7 +40,6 @@ galera_parallel_simple : MDEV-13549 Galera test failures
 galera_admin : MDEV-13549 Galera test failures
 galera_pc_ignore_sb : MDEV-13549 Galera test failures 10.1
 galera_lock_table : MDEV-13549 Galera test failures 10.1
-MW-284 : MDEV-13549 Galera test failures 10.1
 galera_gtid : MDEV-13549 Galera test failures 10.1
 galera_unicode_identifiers : MDEV-13549 Galera test failures 10.1
 galera.galera_gcs_fc_limit : MDEV-13549 Galera test failures 10.1

mysql-test/suite/galera/r/MW-284.result

@@ -14,3 +14,6 @@ STOP SLAVE;
 RESET SLAVE ALL;
 CALL mtr.add_suppression('failed registering on master');
 CALL mtr.add_suppression('You need to use --log-bin to make --binlog-format work');
+RESET MASTER;
+CALL mtr.add_suppression('WSREP: Last Applied Action message in non-primary configuration from member');
+CALL mtr.add_suppression('WSREP: Last Applied Action message in non-primary configuration from member');

mysql-test/suite/galera/t/MW-284.test

@@ -24,7 +24,6 @@ SET global wsrep_sync_wait=0;
 
 --connection node_3
 START SLAVE;
---sleep 1
 --let $slave_param= Slave_IO_Running
 --let $slave_param_value= Connecting
 --source include/wait_for_slave_param.inc
@@ -38,6 +37,7 @@ SET GLOBAL wsrep_provider_options='gmcast.isolate=0';
 --source include/wait_for_slave_to_start.inc
 
 --connection node_1
+--source include/galera_wait_ready.inc
 INSERT INTO t1 VALUES (1);
 
 --connection node_3
@@ -61,3 +61,10 @@ RESET SLAVE ALL;
 
 CALL mtr.add_suppression('failed registering on master');
 CALL mtr.add_suppression('You need to use --log-bin to make --binlog-format work');
+
+--connection node_1
+RESET MASTER;
+CALL mtr.add_suppression('WSREP: Last Applied Action message in non-primary configuration from member');
+
+--connection node_2
+CALL mtr.add_suppression('WSREP: Last Applied Action message in non-primary configuration from member');

sql/sql_parse.cc

@@ -1094,9 +1094,11 @@ bool do_command(THD *thd)
       Bail out if DB snapshot has not been installed.
     */
     if (!thd->wsrep_applier &&
-      (!wsrep_ready || wsrep_reject_queries != WSREP_REJECT_NONE) &&
-      (server_command_flags[command] & CF_SKIP_WSREP_CHECK) == 0)
+        (!wsrep_ready || wsrep_reject_queries != WSREP_REJECT_NONE) &&
+        (server_command_flags[command] & CF_SKIP_WSREP_CHECK) == 0)
     {
+      my_message(ER_UNKNOWN_COM_ERROR,
+                 "WSREP has not yet prepared node for application use", MYF(0));
       thd->protocol->end_statement();
 
       /* Performance Schema Interface instrumentation end. */