BUG #8118: Wrong sorting text

The following bug has been logged on the website:

Bug reference:      8118
Logged by:          whiplash
Email address:      whiplash@bss.org.ua
PostgreSQL version: 9.2.2
Operating system:   Linux (Fedora 11, Fedora 16 and Ubuntu 12.04)
Description:        =


I execute query (1):

SELECT t.name
FROM
(
    SELECT 'AAA AAA' AS name
    UNION ALL
    SELECT 'AAA_AAA'
    UNION ALL =

    SELECT 'BBB_AAA'
    UNION ALL
    SELECT 'BBB AAB'
) t
ORDER BY t.name

and I getting a result:

AAA AAA
AAA_AAA
BBB_AAA
BBB AAB

I think this is result more correct:

AAA AAA
AAA_AAA
BBB AAB
BBB_AAA

On Windows 7 and FreeBSD 9.x query (1) returns correct result.