Assertion `cost > 0.0' failed in adjust_quick_cost

CREATE TABLE t1 (i1 int PRIMARY KEY) ENGINE=MyISAM ;

CREATE TABLE t2 (i1 int PRIMARY KEY) ENGINE=MyISAM ;

CREATE TABLE t3 (i1 int PRIMARY KEY) ENGINE=MRG_MyISAM UNION=(t1,t2) ;

SET  SESSION optimizer_switch = 'index_merge_sort_union=off';

SELECT 1 FROM t1,t3 WHERE t1.i1 = t3.i1 AND t3.i1 < 'a';

#3  <signal handler called>

#4  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50

#5  0x00007fbcad94b535 in __GI_abort () at abort.c:79

#6  0x00007fbcad94b40f in __assert_fail_base (fmt=0x7fbcadaadee0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x563d6eea202e "cost > 0.0", file=0x563d6eea0e78 "/10.5/sql/sql_select.cc", line=7284, function=<optimized out>) at assert.c:92

#7  0x00007fbcad959102 in __GI___assert_fail (assertion=0x563d6eea202e "cost > 0.0", file=0x563d6eea0e78 "/10.5/sql/sql_select.cc", line=7284, function=0x563d6eea5ac0 <adjust_quick_cost(double, unsigned long long)::__PRETTY_FUNCTION__> "double adjust_quick_cost(double, ha_rows)") at assert.c:101

#8  0x0000563d6e164670 in adjust_quick_cost (quick_cost=0.14499999999999999, records=1) at /10.5/sql/sql_select.cc:7284

#9  0x0000563d6e16504e in best_access_path (join=0x7fbc980171c8, s=0x7fbc98018100, remaining_tables=2, join_positions=0x7fbc980186c8, idx=1, disable_jbuf=true, record_count=1, pos=0x7fbc980187f8, loose_scan_pos=0x7fbca830af70) at /10.5/sql/sql_select.cc:7516

#10 0x0000563d6e16ac54 in best_extension_by_limited_search (join=0x7fbc980171c8, remaining_tables=2, idx=1, record_count=1, read_time=0, search_depth=62, prune_level=1, use_cond_selectivity=4) at /10.5/sql/sql_select.cc:9537

#11 0x0000563d6e168c96 in greedy_search (join=0x7fbc980171c8, remaining_tables=2, search_depth=62, prune_level=1, use_cond_selectivity=4) at /10.5/sql/sql_select.cc:8742

#12 0x0000563d6e167f14 in choose_plan (join=0x7fbc980171c8, join_tables=2) at /10.5/sql/sql_select.cc:8307

#13 0x0000563d6e15fad1 in make_join_statistics (join=0x7fbc980171c8, tables_list=..., keyuse_array=0x7fbc980174b8) at /10.5/sql/sql_select.cc:5554

#14 0x0000563d6e153962 in JOIN::optimize_inner (this=0x7fbc980171c8) at /10.5/sql/sql_select.cc:2260

#15 0x0000563d6e151282 in JOIN::optimize (this=0x7fbc980171c8) at /10.5/sql/sql_select.cc:1606

#16 0x0000563d6e15c6cb in mysql_select (thd=0x7fbc98000d78, tables=0x7fbc980141b8, fields=..., conds=0x7fbc980158d8, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2147748608, result=0x7fbc980171a0, unit=0x7fbc98004d80, select_lex=0x7fbc98013c60) at /10.5/sql/sql_select.cc:4654

#17 0x0000563d6e14c42a in handle_select (thd=0x7fbc98000d78, lex=0x7fbc98004cb8, result=0x7fbc980171a0, setup_tables_done_option=0) at /10.5/sql/sql_select.cc:417

#18 0x0000563d6e111c83 in execute_sqlcom_select (thd=0x7fbc98000d78, all_tables=0x7fbc980141b8) at /10.5/sql/sql_parse.cc:6168

#19 0x0000563d6e1087c2 in mysql_execute_command (thd=0x7fbc98000d78) at /10.5/sql/sql_parse.cc:3901

#20 0x0000563d6e116bb2 in mysql_parse (thd=0x7fbc98000d78, rawbuf=0x7fbc98013b90 "SELECT 1 FROM t1,t3 WHERE t1.i1 = t3.i1 AND t3.i1 < 'a'", length=55, parser_state=0x7fbca830c510, is_com_multi=false, is_next_command=false) at /10.5/sql/sql_parse.cc:7953

#21 0x0000563d6e102546 in dispatch_command (command=COM_QUERY, thd=0x7fbc98000d78, packet=0x7fbc98008d09 "SELECT 1 FROM t1,t3 WHERE t1.i1 = t3.i1 AND t3.i1 < 'a'", packet_length=55, is_com_multi=false, is_next_command=false) at /10.5/sql/sql_parse.cc:1839

#22 0x0000563d6e100c84 in do_command (thd=0x7fbc98000d78) at /10.5/sql/sql_parse.cc:1358

#23 0x0000563d6e2a24f2 in do_handle_one_connection (connect=0x563d71d15778, put_in_cache=true) at /10.5/sql/sql_connect.cc:1422

#24 0x0000563d6e2a2222 in handle_one_connection (arg=0x563d71c34c18) at /10.5/sql/sql_connect.cc:1319

#25 0x0000563d6e7d1181 in pfs_spawn_thread (arg=0x563d71d153b8) at /10.5/storage/perfschema/pfs.cc:2201

#26 0x00007fbcae3f1fa3 in start_thread (arg=<optimized out>) at pthread_create.c:486

#27 0x00007fbcada224cf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95