[Draft] pure virtual method called in or around handler::ha_external_lock upon downgrade from newer 10.2

Version: '10.2.18-MariaDB-log'  socket: '/home/travis/logs/current1_1/mysql.sock'  port: 13000  MariaDB Server

pure virtual method called

terminate called without an active exception

181027  4:03:34 [ERROR] mysqld got signal 6 ;

Server version: 10.2.18-MariaDB-log

key_buffer_size=134217728

read_buffer_size=131072

max_used_connections=5

max_threads=153

thread_count=11

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 467249 K  bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7f0300000a88

Attempting backtrace. You can use the following information to find out

where mysqld died. If you see no messages after this, something went

terribly wrong...

stack_bottom = 0x7f036414fe80 thread_stack 0x49000

mysys/stacktrace.c:268(my_print_stacktrace)[0x55e34b081e1b]

sql/signal_handler.cc:168(handle_fatal_signal)[0x55e34ab4c9b5]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7f0367d84330]

/lib/x86_64-linux-gnu/libc.so.6(gsignal+0x37)[0x7f03673d7c37]

/lib/x86_64-linux-gnu/libc.so.6(abort+0x148)[0x7f03673db028]

/usr/lib/x86_64-linux-gnu/libstdc++.so.6(_ZN9__gnu_cxx27__verbose_terminate_handlerEv+0x155)[0x7f0367ad0535]

/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e6d6)[0x7f0367ace6d6]

/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5e703)[0x7f0367ace703]

/usr/lib/x86_64-linux-gnu/libstdc++.so.6(+0x5f1bf)[0x7f0367acf1bf]

sql/handler.cc:5895(handler::ha_external_lock(THD*, int))[0x55e34ab55f33]

sql/lock.cc:719(unlock_external)[0x55e34ac12ffb]

sql/lock.cc:429(mysql_unlock_tables(THD*, st_mysql_lock*, bool))[0x55e34ac132bc]

sql/sql_base.cc:844(close_thread_tables(THD*))[0x55e34a984cb7]

sql/sql_parse.cc:6305(mysql_execute_command(THD*))[0x55e34a9c7569]

sql/sql_parse.cc:8011(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x55e34a9cf3ca]

sql/sql_parse.cc:1824(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x55e34a9d17f1]

sql/sql_parse.cc:1380(do_command(THD*))[0x55e34a9d1ddd]

sql/sql_connect.cc:1335(do_handle_one_connection(CONNECT*))[0x55e34aa9210f]

sql/sql_connect.cc:1243(handle_one_connection)[0x55e34aa92234]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x8184)[0x7f0367d7c184]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f036749effd]

Trying to get some variables.

Some pointers may be invalid and cause the dump to abort.

Query (0x7f030000f140): UPDATE `t7` SET `col_char` = 'o' WHERE `pk` = 2099 /* QNO 1275 CON_ID 15 */

Connection ID (thread ID): 15

Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=off,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on

perl /home/travis/rqg//runall-new.pl --grammar=conf/mariadb/oltp-transactional.yy --grammar2=conf/mariadb/oltp_and_ddl.yy --gendata=conf/mariadb/innodb_upgrade.zz --gendata-advanced --mysqld=--server-id=111 --scenario=Upgrade --duration=90 --basedir2=/home/travis/old --basedir1=/home/travis/server --mysqld=--innodb-page-size=8K --mysqld=--innodb-compression-algorithm=none --mysqld=--loose-innodb-file-format=Barracuda --mysqld=--loose-innodb-file-per-table=1 --gendata=conf/mariadb/innodb_upgrade.zz --no-mask --seed=1540611984 --threads=4 --queries=100M --mysqld=--loose-max-statement-time=20 --mysqld=--loose-lock-wait-timeout=20 --mysqld=--loose-innodb-lock-wait-timeout=10 --mysqld=--loose-innodb_log_compressed_pages=on --mtr-build-thread=300 --vardir1=/home/travis/logs/current1_1