qtqa tests are unstable on Ubuntu 12.04 x64

 + prove -I /work/build/qt/qtqa/scripts/lib/perl5 --merge --state=save -I /work/build/qt/qtqa/scripts/lib/perl5 --recurse /work/build/qt/qtqa/scripts
/work/build/qt/qtqa/scripts/generic/t/01-coveragerunner_testcocoon.t ...................... ok
/work/build/qt/qtqa/scripts/generic/t/01-testrunner-testcocoon.t .......................... ok
/work/build/qt/qtqa/scripts/generic/t/01-xml2html_testcocoon.t ............................ ok
/work/build/qt/qtqa/scripts/generic/t/10-testrunner.t ..................................... ok
/work/build/qt/qtqa/scripts/generic/t/15-testrunner-capture-logs.t ........................ ok
/work/build/qt/qtqa/scripts/generic/t/16-testrunner-capture-logs-race.t ................... ok
/work/build/qt/qtqa/scripts/generic/t/20-testrunner-core.t ................................
Dubious, test returned 4 (wstat 1024, 0x400)
Failed 4/27 subtests
/work/build/qt/qtqa/scripts/generic/t/21-testrunner-flaky.t ...............................
Dubious, test returned 4 (wstat 1024, 0x400)
Failed 4/72 subtests
/work/build/qt/qtqa/scripts/generic/t/22-testrunner-sync-output.t ......................... ok
/work/build/qt/qtqa/scripts/generic/t/23-testrunner-crashreporter.t ....................... skipped: test is not relevant on linux
/work/build/qt/qtqa/scripts/generic/t/30-parse_build_log.t ................................ ok
/work/build/qt/qtqa/scripts/generic/t/40-testplanner.t .................................... ok
/work/build/qt/qtqa/scripts/generic/t/41-print_calling_makefile.t ......................... skipped: This test is relevant only on Win32 and nmake
/work/build/qt/qtqa/scripts/generic/t/50-testscheduler.t .................................. ok
/work/build/qt/qtqa/scripts/git/t/10-git-qtqa-combine.t ................................... ok
/work/build/qt/qtqa/scripts/jenkins/t/05-qt-jenkins-integrator.t .......................... ok
/work/build/qt/qtqa/scripts/jenkins/t/10-summarize-jenkins-build.t ........................ ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/Proc/Reliable/t/01-QtQA-Proc-Reliable-Win32.t .. ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/Proc/t/10-reliable.t ........................... ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/Proc/t/20-reliable-strategies.t ................ ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/Test/t/10-test-more-create_mock_command.t ...... ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/t/10-Gerrit.t .................................. ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/t/10-TestScript.t .............................. ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/t/20-TestScript-autodocs.t ..................... ok
/work/build/qt/qtqa/scripts/lib/perl5/QtQA/t/30-TestScript-reliable-exe.t ................. ok
/work/build/qt/qtqa/scripts/t/10-perl-syntax-check.t ...................................... ok
/work/build/qt/qtqa/scripts/t/20-perl-critic-check.t ...................................... ok
/work/build/qt/qtqa/scripts/t/90-licenses.t ............................................... ok

Test Summary Report
-------------------
/work/build/qt/qtqa/scripts/generic/t/20-testrunner-core.t (Wstat: 1024 Tests: 27 Failed: 4)
Failed tests: 17, 22, 25, 27
Non-zero exit status: 4
/work/build/qt/qtqa/scripts/generic/t/21-testrunner-flaky.t (Wstat: 1024 Tests: 72 Failed: 4)
Failed tests: 65, 67, 70, 72
Non-zero exit status: 4
Files=28, Tests=1403, 237 wallclock secs ( 0.32 usr 0.06 sys + 168.23 cusr 12.08 csys = 180.69 CPU)
Result: FAIL