[regression] parse_build_log fails to extract test failures

From this log, parse_build_log failed to extract the tst_qfile failure message: http://testresults.qt-project.org/ci/QtBase_master_Integration/build_03021/win32-msvc2010_developer-build_qtnamespace_Windows_7/log.txt.gz

It may be due to the new "run concurrently" messages.