HPCC-10965 Open Legacy ECL Watch Fails on FF

Fixes HPCC-10965

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge branch 'HPCC-10965' into candidate-4.2.4

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge remote-tracking branch 'origin/candidate-4.2.4' into closedown-4.2.x

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>