mongodb reconnect test is too slow

Ran 3008 tests in 619.459s
PASSED (id=0, skips=216)
Slowest Tests
Test id Runtime (s)
--------------------------------------------------------------------------------------------------------------------------------------- -----------
ceilometer.tests.storage.test_storage_scenarios.MongoAutoReconnectTest.test_mongo_update(mongodb) 10.165
ceilometer.tests.storage.test_storage_scenarios.MongoAutoReconnectTest.test_mongo_find_and_modify(mongodb) 10.157
ceilometer.tests.storage.test_storage_scenarios.MongoAutoReconnectTest.test_mongo_insert(mongodb) 10.149
ceilometer.tests.storage.test_storage_scenarios.MongoAutoReconnectTest.test_mongo_find(mongodb) 10.134
ceilometer.tests.publisher.test_messaging_publisher.TestPublisher.test_published_with_policy_default_sized_queue_and_rpc_down(notifier) 4.976
ceilometer.tests.publisher.test_messaging_publisher.TestPublisher.test_published_with_policy_default_sized_queue_and_rpc_down(rpc) 4.840
ceilometer.tests.storage.test_storage_scenarios.ComplexAlarmHistoryQueryTest.test_alarm_history_with_no_filter_and_limit(sqlite) 3.336
ceilometer.tests.storage.test_storage_scenarios.StatisticsGroupByTest.test_group_by_end_timestamp_before(sqlite) 3.136
ceilometer.tests.ipmi.platform.test_intel_node_manager.TestNonNodeManager.test_read_temperature_all 3.005
ceilometer.tests.storage.test_storage_scenarios.ComplexSampleQueryTest.test_query_complex_filter_with_limit(sqlite) 2.919

This is because retry_interval is default 10 seconds, we need to override that value in unit test, no need to wait for 10 seconds, then we can reduce 36 seconds when we run unittest, yes!!