Some of our existing Marionette tests and also upcoming Firefox ui tests require remote testcase data. As such we should not run those tests as Tier-1 but Tier-2. We have to find a way to split up the tests. Please note that right now Marionette doesn't support MOZ_DISABLE_NONLOCAL_CONNECTIONS. So current Tier-1 tests which accessing remote testcase data do not crash Firefox. Once we have fixed that bug, we should be able to enable support for this feature in Marionette. This will make our Tier-1 suites more stable.