LP:925377 - Querying myisam table metadata while 'alter table..enable keys' is running may corrupt the table

In MariaDB 5.3.3 tables are reported as corrupted in the server log when metadata queries like "show table status like 'tablename'" or "select ..from information_schemna where table_schema = 'dbname'
AND a.table_name LIKE 'tablename'" are run while indexes are getting rebuilt with "alter table tablename enable keys".

I can consistently replicate the problem in MariaDB 5.3.3 (mariadb-5.3.3-rc-Linux-x86_64.tar.gz) running on RHEL 5.7 and RHEL 6.1.

An error like

[ERROR] mysqld: Table './dbname/tablename' is marked as crashed and should be repaired

gets logged in the server log just as the metadata query is getting submitted. The query remains in a "Waiting for table" state and will return only after the "alter table enable keys" query ends.
Running "check table" or "repair table" after "alter table enable keys" won't report any problems.

Use this script to reproduce the problem:

#!/bin/sh

HOST=localhost
PORT=3306
USER=
PASSWORD=
DATABASE=test
MYSQL_CLIENT=/usr/bin/mysql
TABLE=reproducer
DATAFILE=reproducer.txt

function generate_file {
echo "Generating data file $DATAFILE.."
for i in

do
echo "$i,line number $i" >> $DATAFILE
done
}

function run_cmd {
echo "Running -> '$1'"
$MYSQL_CLIENT --host=$HOST --user=$USER --password=$PASSWORD --database=$DATABASE --exec="$1"
}

generate_file

run_cmd "drop table if exists $TABLE"
run_cmd "create table $TABLE (id int, sometext varchar(100), primary key (id), index(sometext)) ENGINE=myisam"
run_cmd "alter table $TABLE disable keys"
run_cmd "load data local infile '$DATAFILE' into table $TABLE fields terminated by ','"

run_cmd "alter table $TABLE enable keys" &
sleep 1
run_cmd "show table status like '$TABLE'"