Some slow_extended incorrect work on slow machines (or valgrind)

Actual for:
 * x86_64
 * Fedora 14
 * Release
Failed tests:
 * percona_slow_extended-log_slow_filter
 * percona_slow_extended-long_query_time
 * percona_slow_extended-microseconds_in_slow_extended
 * percona_slow_extended-min_examined_row_limit
 * percona_slow_extended-use_global_long_query_time
Detail information:
oleg.tsarev (0) (dir)$ uname -a
Linux t510 2.6.35.13-91.fc14.x86_64 #1 SMP Tue May 3 13:23:06 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

oleg.tsarev (0) (dir)$ cat /etc/issue
Fedora release 14 (Laughlin)
Kernel \r on an \m (\l)

Fail outputs:
oleg.tsarev (0) (dir)$ ./mysql-test-run --valgrind percona_slow_extended-log_slow_filter
Logging: (dir)/mysql-test-run.pl --valgrind percona_slow_extended-log_slow_filter
110608 4:42:48 [Note] Flashcache bypass: disabled
110608 4:42:48 [Note] Flashcache setup error is : open flash device failed

MySQL Version 5.5.12
Too long tmpdir path '(dir)/var/tmp' creating a shorter one...
 - using tmpdir: '/tmp/ZlOomEyvoW'

Turning on valgrind for all executables
Running valgrind with options " --show-reachable=yes "
Checking supported features...
 - skipping ndbcluster
 - skipping SSL, mysqld not compiled with SSL
Collecting tests...
vardir: (dir)/var
Removing old var directory...
Creating var directory '(dir)/var'...
Installing system database...
Using server port 33151

==============================================================================

TEST RESULT TIME (ms) or COMMENT
--------------------------------------------------------------------------

worker[1] Using MTR_BUILD_THREAD 301, with reserved ports 13010..13019
main.percona_slow_extended-log_slow_filter [ fail ]
        Test ended at 2011-06-08 04:43:12

CURRENT_TEST: main.percona_slow_extended-log_slow_filter
==2551== Memcheck, a memory error detector
==2551== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al.
==2551== Using Valgrind-3.5.0 and LibVEX; rerun with -h for copyright info
==2551== Command: /storage/dev/percona/5.5.12-786645-slow_extended/Percona-Server-5.5.12-rel20.3-release/client//mysqltest --defaults-file=(dir)/var/my.cnf --silent --tmpdir=/tmp/ZlOomEyvoW --character-sets-dir=/storage/dev/percona/5.5.12-786645-slow_extended/Percona-Server-5.5.12-rel20.3/sql/share/charsets --logdir=(dir)/var/log --plugin_dir=/storage/dev/percona/5.5.12-786645-slow_extended/Percona-Server-5.5.12-rel20.3-release/plugin/auth --database=test --timer-file=(dir)/var/log/timer --test-file=(dir)/t/percona_slow_extended-log_slow_filter.test --tail-lines=20 --result-file=(dir)/r/percona_slow_extended-log_slow_filter.result
==2551==
--- (dir)/r/percona_slow_extended-log_slow_filter.result 2011-06-08 04:37:22.645474087 +0300
+++ (dir)/r/percona_slow_extended-log_slow_filter.reject 2011-06-08 04:43:11.761645253 +0300
@@ -22,4 +22,4 @@
 0
 drop table if exists t;
 FLUSH LOGS;
-2
+3

mysqltest: Result content mismatch

==2551==
==2551== HEAP SUMMARY:
==2551== in use at exit: 0 bytes in 0 blocks
==2551== total heap usage: 342 allocs, 342 frees, 546,663 bytes allocated
==2551==
==2551== All heap blocks were freed -- no leaks are possible
==2551==
==2551== For counts of detected and suppressed errors, rerun with: -v
==2551== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 6)

 - saving '(dir)/var/log/main.percona_slow_extended-log_slow_filter/' to '(dir)/var/log/main.percona_slow_extended-log_slow_filter/'
--------------------------------------------------------------------------
The servers were restarted 0 times
Spent 0.000 of 24 seconds executing testcases

Completed: Failed 1/1 tests, 0.00% were successful.

Failing test(s): main.percona_slow_extended-log_slow_filter

The log files in var/log may give you some hint of what went wrong.

If you want to report this error, please read first the documentation
at http://dev.mysql.com/doc/mysql/en/mysql-test-suite.html

mysql-test-run: *** ERROR: there were failing test cases
oleg.tsarev (0) (dir)$