virtual bool Item_cache::is_expensive(): Assertion `example' failed.

[sbester]

mysqld: ./maria-5.5/sql/item.h:3892: virtual bool Item_cache::is_expensive(): Assertion `example' failed.

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7ffff42d3700 (LWP 29894)]
0x00000030b84330c5 in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
64 return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
(gdb) bt
#0 in raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1 in abort () at abort.c:92
#2 in __assert_fail at assert.c:81
#3 in Item_cache::is_expensive at ./maria-5.5/sql/item.h:3892
#4 in make_join_statistics at ./maria-5.5/sql/sql_select.cc:3455
#5 in JOIN::optimize at ./maria-5.5/sql/sql_select.cc:1195
#6 in mysql_select at ./maria-5.5/sql/sql_select.cc:3000
#7 in handle_select at ./maria-5.5/sql/sql_select.cc:311
#8 in execute_sqlcom_select at ./maria-5.5/sql/sql_parse.cc:4616
#9 in mysql_execute_command at ./maria-5.5/sql/sql_parse.cc:2184
#10 in mysql_parse at ./maria-5.5/sql/sql_parse.cc:5731
#11 in dispatch_command at ./maria-5.5/sql/sql_parse.cc:1055
#12 in do_command at ./maria-5.5/sql/sql_parse.cc:794
#13 in do_handle_one_connection at ./maria-5.5/sql/sql_connect.cc:1253
#14 in handle_one_connection at ./maria-5.5/sql/sql_connect.cc:1168
#15 in start_thread at pthread_create.c:301
#16 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

How to repeat:
------------------
#on a debug build:

drop table if exists `t1`;
create table `t1`(`a` date,key(`a`))engine=innodb;
insert into `t1` values ('2012-01-01'),('2012-02-02');
select 1 from `t1` as `t1_0` inner join `t1` as `t2`
on (`t1_0`.`a` <=> now()) join `t1` on 1;

[Elena Stepanova (elenst)]

Reproducible also with MyISAM and Aria, and on 5.3 as well as 5.5.
No visible effect on a release build.