HPCC-11896 Spurious regression suite failure on superfile6 test

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #6223 from richardkchapman/superfile6-test

HPCC-11896 Spurious regression suite failure on superfile6 test

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>