This is the corner case of ONLINE ALTER vs ha_maria vs App-time Periods.

When a Delete_rows_event (or update) is executed, a lookup handler may be
created, normally to serve long unique index needs, by a call of
handler::prepare_for_insert. This function also creates a lookup handler
if an application-time period exists in a table.

A difference with a usual call of prepare_for_insert is that transactions
are disabled for this table during ALTER TABLE. See
mysql_trans_prepare_alter_copy_data call in copy_data_between_tables.

Then, ha_maria calls _ma_tmp_disable_logging_for_table during
ha_maria::external_lock. It never happened so before, that two handlers
would be created for write to a single ha_maria table under transactions
disabled.

Hence, the fix handles this scenario.
It could be done otherwise, by not creating this lookup handler (since it's
not used anyway during ONLINE ALTER), but architecturally, two handlers
should be supported.

Avoiding the creation of lookup handler could be done here additionally,
but with a cost of slowing down other more generic cases, with an
additional check of online alter table active.