Valgrind warnings in ha_maria::check_if_incompatible_data on an attempt to alter a partitioned Aria table to an unknown engine

Conditional jump or move depends on uninitialised value(s)

   at 0x966037: ha_maria::check_if_incompatible_data(st_ha_create_information*, unsigned int) (ha_maria.cc:3191)

   by 0xC7E657: ha_partition::check_if_incompatible_data(st_ha_create_information*, unsigned int) (ha_partition.cc:6989)

   by 0x6AC739: mysql_compare_tables(TABLE*, Alter_info*, st_ha_create_information*, unsigned int, enum_alter_table_change_level*, st_key**, unsigned int**, unsigned int*, unsigned int**, unsigned int*, unsigned int*) (sql_table.cc:5369)

   by 0x6AF306: mysql_alter_table(THD*, char*, char*, st_ha_create_information*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool, bool) (sql_table.cc:6404)

   by 0x9406CD: Alter_table_statement::execute(THD*) (sql_alter.cc:106)

   by 0x615175: mysql_execute_command(THD*) (sql_parse.cc:4771)

   by 0x618393: mysql_parse(THD*, char*, unsigned int, Parser_state*) (sql_parse.cc:6056)

   by 0x60B33F: dispatch_command(enum_server_command, THD*, char*, unsigned int) (sql_parse.cc:1216)

   by 0x60A538: do_command(THD*) (sql_parse.cc:945)

   by 0x70F63F: do_handle_one_connection(THD*) (sql_connect.cc:1254)

   by 0x70F00F: handle_one_connection (sql_connect.cc:1168)

   by 0xBE083A: pfs_spawn_thread (pfs.cc:1800)

   by 0x5895EFB: start_thread (pthread_create.c:304)

   by 0x611959C: clone (clone.S:112)

--source include/have_partition.inc

CREATE TABLE t1 (a INT) ENGINE=Aria PARTITION BY HASH(a) PARTITIONS 2;

ALTER TABLE t1 ENGINE = Unknown;