[Draft] Assertion `user_table->get_ref_count() == 1' failed in commit_try_rebuild

mysqld: /home/travis/src/storage/innobase/handler/handler0alter.cc:8749: bool commit_try_rebuild(Alter_inplace_info*, ha_innobase_inplace_ctx*, TABLE*, const TABLE*, trx_t*, const char*): Assertion `user_table->get_ref_count() == 1' failed.

181026  6:14:43 [ERROR] mysqld got signal 6 ;

/lib/x86_64-linux-gnu/libc.so.6(+0x2fca2)[0x7f4a38ef0ca2]

handler/handler0alter.cc:8751(commit_try_rebuild(Alter_inplace_info*, ha_innobase_inplace_ctx*, TABLE*, TABLE const*, trx_t*, char const*))[0x55e255e8645c]

handler/handler0alter.cc:9647(ha_innobase::commit_inplace_alter_table(TABLE*, Alter_inplace_info*, bool))[0x55e255e80249]

sql/handler.cc:4457(handler::ha_commit_inplace_alter_table(TABLE*, Alter_inplace_info*, bool))[0x55e255c2fd1a]

sql/sql_table.cc:7615(mysql_inplace_alter_table)[0x55e255a06c73]

sql/sql_table.cc:9711(mysql_alter_table(THD*, st_mysql_const_lex_string const*, st_mysql_const_lex_string const*, HA_CREATE_INFO*, TABLE_LIST*, Alter_info*, unsigned int, st_order*, bool))[0x55e255a0cad1]

sql/sql_alter.cc:497(Sql_cmd_alter_table::execute(THD*))[0x55e255a9592a]

sql/sql_parse.cc:6285(mysql_execute_command(THD*))[0x55e255936bcf]

sql/sql_parse.cc:8091(mysql_parse(THD*, char*, unsigned int, Parser_state*, bool, bool))[0x55e25593bc6e]

sql/sql_parse.cc:1852(dispatch_command(enum_server_command, THD*, char*, unsigned int, bool, bool))[0x55e255928e7e]

sql/sql_parse.cc:1395(do_command(THD*))[0x55e2559278af]

sql/sql_connect.cc:1402(do_handle_one_connection(CONNECT*))[0x55e255a8ff18]

sql/sql_connect.cc:1309(handle_one_connection)[0x55e255a8fc9c]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x8184)[0x7f4a39ab2184]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x6d)[0x7f4a38fbeffd]

Trying to get some variables.

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

Query (0x7f4a34158338): ALTER TABLE `t5` FORCE  /* QNO 931 CON_ID 16 */

Connection ID (thread ID): 29

Status: NOT_KILLED

perl ./runall-new.pl --basedir=/home/travis/server --vardir=/home/travis/logs/vardir --duration=350 --threads=6 --seed=1540534449 --reporters=Backtrace,ErrorLog,Deadlock --validators=TransformerNoComparator --views --redefine=conf/mariadb/alter_table.yy --redefine=conf/mariadb/sp.yy --redefine=conf/mariadb/bulk_insert.yy --redefine=conf/mariadb/versioning.yy --redefine=conf/mariadb/sequences.yy --mysqld=--log_output=FILE --mysqld=--max-statement-time=30 --mysqld=--lock-wait-timeout=10 --mysqld=--loose-innodb-lock-wait-timeout=5 --mysqld=--loose-debug_assert_on_not_freed_memory=0 --mysqld=--default-storage-engine=MyISAM --grammar=conf/runtime/WL5004_sql.yy --gendata=conf/runtime/WL5004_data.zz --skip-gendata --gendata-advanced --vcols --transformers=ExecuteAsIntersect,ExecuteAsExcept,ExecuteAsCTE,ExecuteAsExecuteImmediate,ExecuteAsDeleteReturning,ExecuteAsInsertSelect,ExecuteAsUnion,ExecuteAsUpdateDelete,ExecuteAsView,ExecuteAsPreparedTwice