Bug #16893 Crash in test 'fulltext_order_by'

Description:
Release build of 4.1.18, based on ChangeSet
  1.2463 06/01/27 13:38:15 kent@mysql.com +1 -0
  disabled.def:
    Enabled rpl_* tests now when bug fixed

Crash occurred only once:
=====
fulltext_order_by              [ fail ]

Errors are (from PATH/mysqltest-time) :
mysqltest: At line NNN: query '(select b.id, b.betreff from t3 b) union
(select b.id, b.betreff from t3 b)
order by match(betreff) against ('+abc') desc' failed with wrong errno 2013 instead of 1191...
mysqltest: At line NNN: unable to send query 'select distinct b.id, b.betreff from t3 b
order by match(betreff) against ('+abc' in boolean mode) desc' (mysql_errno=2002 , errno=61)
(the last lines may be the most important ones)
=====

How to repeat:
Detected by running the test suite.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/2120

Fixed that fulltext query + union results in unexpected behaviour.

Fixed in 4.1.19. This bug was already fixed in 5.0 and up in Semptember 2005.

Noted in 4.1.19 changelog.

        <para>
          A <literal>FULLTEXT</literal> query in a
          <literal>UNION</literal> could result in unexpected behavior.
          (Bug #16893)
        </para>