MDEV-9453 mysql_upgrade.exe error when mysql is migrated to mariadb

mysqlcheck tool can be used even if opt_systables_only is true
(to upgrade views from mysql - that overrides opt_systables_only)

client/mysql_upgrade.c

@@ -1051,16 +1051,11 @@ int main(int argc, char **argv)
   /* Find mysql */
   find_tool(mysql_path, IF_WIN("mysql.exe", "mysql"), self_name);
 
-  if (!opt_systables_only)
-  {
-    /* Find mysqlcheck */
-    find_tool(mysqlcheck_path, IF_WIN("mysqlcheck.exe", "mysqlcheck"), self_name);
-  }
-  else
-  {
-    if (!opt_silent)
-      printf("The --upgrade-system-tables option was used, databases won't be touched.\n");
-  }
+  /* Find mysqlcheck */
+  find_tool(mysqlcheck_path, IF_WIN("mysqlcheck.exe", "mysqlcheck"), self_name);
+
+  if (opt_systables_only && !opt_silent)
+    printf("The --upgrade-system-tables option was used, user tables won't be touched.\n");
 
   /*
     Read the mysql_upgrade_info file to check if mysql_upgrade

mysql-test/r/mysql_upgrade.result

@@ -250,7 +250,7 @@ GRANT USAGE ON *.* TO 'user3'@'%'
 GRANT ALL PRIVILEGES ON `roelt`.`test2` TO 'user3'@'%'
 DROP USER 'user3'@'%';
 End of 5.1 tests
-The --upgrade-system-tables option was used, databases won't be touched.
+The --upgrade-system-tables option was used, user tables won't be touched.
 Phase 1/4: Fixing views... Skipped
 Phase 2/4: Fixing table and database names ... Skipped
 Phase 3/4: Checking and upgrading tables... Skipped

mysql-test/r/mysql_upgrade_view.result

@@ -266,4 +266,19 @@ master-bin.000001	#	Query	#	#	use `test`; REPAIR VIEW `v3`  FROM MYSQL
 master-bin.000001	#	Query	#	#	use `test`; REPAIR VIEW `v4`  FROM MYSQL
 drop table if exists kv;
 drop view v1,v2,v3,v4;
+rename table mysql.event to mysql.ev_bk;
+flush tables;
+The --upgrade-system-tables option was used, user tables won't be touched.
+MySQL upgrade detected
+Phase 1/4: Fixing views from mysql
+test.v1                                            OK
+test.v2                                            OK
+test.v3                                            OK
+Phase 2/4: Fixing table and database names ... Skipped
+Phase 3/4: Checking and upgrading tables... Skipped
+Phase 4/4: Running 'mysql_fix_privilege_tables'
+OK
+drop table mysql.event;
+rename table mysql.ev_bk to mysql.event;
+drop view v1,v2,v3;
 drop table t1;

mysql-test/t/mysql_upgrade_view.test

@@ -157,5 +157,30 @@ rename table mysql.ev_bk to mysql.event;
 
 drop table if exists kv;
 drop view v1,v2,v3,v4;
-drop table t1;
 
+#
+# MDEV-9453 mysql_upgrade.exe error when mysql is migrated to mariadb
+# (mysql_upgrade.exe --upgrade-system-tables fails on fixing views)
+#
+
+# Make it look like a MySQL directory again
+
+rename table mysql.event to mysql.ev_bk;
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/event.MYI $MYSQLD_DATADIR/mysql/event.MYI
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/event.MYD $MYSQLD_DATADIR/mysql/event.MYD
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/event.frm $MYSQLD_DATADIR/mysql/event.frm
+
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/v1.frm $MYSQLD_DATADIR/test/v1.frm
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/v2.frm $MYSQLD_DATADIR/test/v2.frm
+--copy_file $MYSQL_TEST_DIR/std_data/mysql_upgrade/v3.frm $MYSQLD_DATADIR/test/v3.frm
+
+flush tables;
+
+--replace_result $MYSQLTEST_VARDIR var
+--exec $MYSQL_UPGRADE --force --upgrade-system-tables 2>&1
+
+# back to mariadb default
+drop table mysql.event;
+rename table mysql.ev_bk to mysql.event;
+drop view v1,v2,v3;
+drop table t1;