fix test_marker_presence_required
Merge pull request #494 from Incubaid/test-marker-presence

fix test_marker_presence_required
Add `Client_main.find_master_loop`
Attempt to make master lookup in some unit tests more resilient
Merge pull request #496 from Incubaid/unit-test-master-lookup-resilience

Enhance unit test master lookup resilience
fix universe.small_catchup.catchup.batched_with_failures failure
Merge pull request #497 from Incubaid/fix-universe.small_catchup.catchup.batched_with_failures-failure

fix universe.small_catchup.catchup.batched_with_failures failure
Merge branch 'incubaid-1.7' into incubaid-1.6-for-1.7