Robustness fixes for BlockObserverSynchronizationTests (#712)
Robustness fixes for BlockObserverSynchronizationTests (#712)

`test__will_add_synchronized` and `test__did_add_synchronized` could (rarely) hit a race condition in the tests themselves and fail.
ProcedureKit/ProcedureKit,danthorpe/Operations,danthorpe/Operations,danthorpe/Operations,ProcedureKit/ProcedureKit,ProcedureKit/ProcedureKit