LP:933959 - Assertion `0' failed in net_end_statement(THD*) on concurrent SELECT FROM I_S.INNODB_SYS_INDEXES and ALTER TABLE

Version: '5.3.4-MariaDB-rc-debug-log'
mysqld: protocol.cc:509: void net_end_statement(THD*): Assertion `0' failed.

#8 0xb741d014 in __assert_fail () from /lib/libc.so.6
#9 0x082c4fad in net_end_statement (thd=0x9eebc88) at protocol.cc:509
#10 0x082e2484 in dispatch_command (command=COM_QUERY, thd=0x9eebc88,
packet=0x9eede31 "SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_INDEXES", packet_length=51)
at sql_parse.cc:1620
#11 0x082e08df in do_command (thd=0x9eebc88) at sql_parse.cc:923
#12 0x082dd865 in handle_one_connection (arg=0x9eebc88) at sql_connect.cc:1193
#13 0xb76abb25 in start_thread () from /lib/libpthread.so.0

Query (0x9f2e398): SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_INDEXES
Connection ID (thread ID): 4
Status: NOT_KILLED

bzr version-info
revision-id: <email address hidden>
date: 2012-02-16 20:15:57 +0400
build-date: 2012-02-17 07:40:46 +0400
revno: 3424

Also reproducible on MariaDB 5.1 and 5.2.
Could not reproduce on 5.5, but the test is not deterministic., so there is no guarantee. It is, however, noticeable, that the flow works much slower on 5.5

1. MTR test case (please note that the number of attempts is set in the $run variable):

--source include/have_innodb.inc

CREATE TABLE t1 (
a DATE,
b TIME,
c VARCHAR(1),
d INT
) ENGINE=InnoDB;
--connect (con1,127.0.0.1,root,,test)
--connect (con2,127.0.0.1,root,,test)
let $run=1000;
--disable_query_log
--disable_result_log
while ($run)
{
--echo # $run attempts left
--connection con1
--send
ALTER TABLE t1 ADD KEY(d);
--connection con2
SELECT * FROM INFORMATION_SCHEMA.INNODB_SYS_INDEXES;
--connection con1
--reap
ALTER TABLE t1 DROP KEY d;
--dec $run
}

1. End of test case