MDEV-18639 Assertion failure upon attempt to start with lower number of undo tablespaces

trx_rseg_t::is_persistent(): Correct a bogus debug assertion.

mysql-test/suite/innodb/r/undo_truncate_recover.result

@@ -9,6 +9,7 @@ update t1 set c = 'MariaDB';
 update t1 set c = 'InnoDB';
 set global debug_dbug = '+d,ib_undo_trunc';
 commit;
+call mtr.add_suppression("InnoDB: innodb_undo_tablespaces=0 disables dedicated undo log tablespaces");
 call mtr.add_suppression("InnoDB: The transaction log size is too large");
 SET GLOBAL innodb_fast_shutdown=0;
 FOUND 1 /ib_undo_trunc/ in mysqld.1.err

mysql-test/suite/innodb/t/undo_truncate_recover.test

@@ -38,13 +38,14 @@ update t1 set c = 'MariaDB';
 update t1 set c = 'InnoDB';
 eval set global debug_dbug = '+d,$SEARCH_PATTERN';
 commit;
+call mtr.add_suppression("InnoDB: innodb_undo_tablespaces=0 disables dedicated undo log tablespaces");
 # FIXME: remove this work-around, and generate less log!
 call mtr.add_suppression("InnoDB: The transaction log size is too large");
 SET GLOBAL innodb_fast_shutdown=0;
 --source include/shutdown_mysqld.inc
 --source include/search_pattern_in_file.inc
 # FIXME: remove this work-around, and generate less log!
---let $restart_parameters= --innodb-buffer-pool-size=16m
+--let $restart_parameters= --innodb-buffer-pool-size=16m --innodb-undo-tablespaces=1
 --source include/start_mysqld.inc
 
 drop table t1;

storage/innobase/include/trx0rseg.h

@@ -213,7 +213,7 @@ struct trx_rseg_t {
 		      || (srv_undo_space_id_start > 0
 			  && space >= srv_undo_space_id_start
 			  && space <= srv_undo_space_id_start
-			  + srv_undo_tablespaces_active)
+			  + srv_undo_tablespaces_open)
 		      || !srv_was_started);
 		return(space != SRV_TMP_SPACE_ID);
 	}