Frequent failure of ep_testsuite.full_eviction.rocksdb "expiry" test on macOS

[2020-06-30T09:57:03.685Z] Running [0001/0157]: expiry (couchstore)...../kv_engine/engines/ep/tests/ep_testsuite.cc:869 Test failed: `' (Expected `1', got `2' - curr_items stat should be still 1 after overwriting the key that was expired, but not purged yet)

 (62 ms) FAIL

[ RUN      ] AllBackends/DurabilityEPBucketTest.CompactionOfPrepareDoesNotAddToBloomFilter/persistentRocksdb_value_only

 unknown file: Failure

 C++ exception with description "CheckedExecutor failed fetchNextTask" thrown in the test body.

 [  FAILED  ] AllBackends/DurabilityEPBucketTest.CompactionOfPrepareDoesNotAddToBloomFilter/persistentRocksdb_value_only, where GetParam() = ("persistentRocksdb", "value_only") (15 ms)