DrainStatusPoller crash when couch is unavailable
I saw this error in one of the agents this morning
```
2018-11-06 11:10:19,930:139824323180288:ERROR:BaseWorkerThread:Error in worker algorithm (1):
Backtrace:
  <WMComponent.AgentStatusWatcher.DrainStatusPoller.DrainStatusPoller object at 0x7f2b641db910> 'NoneType' object has no attribute 'items'  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python
2.7/site-packages/WMCore/WorkerThreads/BaseWorkerThread.py", line 187, in __call__
    tSpent, results, _ = algorithmWithDBExceptionHandler(parameters)
  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python2.7/site-packages/WMCore/Database/DBExceptionHandler.py", line 28, in wrapper
    return f(*args, **kwargs)
  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python2.7/site-packages/Utils/Timers.py", line 24, in wrapper
    res = func(*arg, **kw)
  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python2.7/site-packages/WMComponent/AgentStatusWatcher/DrainStatusPoller.py", line 47, in algorithm
    thresholdsHit = self.checkSpeedDrainThresholds()
  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python2.7/site-packages/WMComponent/AgentStatusWatcher/DrainStatusPoller.py", line 144, in checkSpeedDrainThresholds
    for k, v in speedDrainConfig.items():

2018-11-06 11:10:19,931:139824323180288:INFO:Harness:>>>Terminating worker threads
2018-11-06 11:10:28,469:139824323180288:ERROR:BaseWorkerThread:Error in event loop (2): <WMComponent.AgentStatusWatcher.DrainStatusPoller.DrainStatusPoller object at 0x7f2b641db910> 'NoneType' object has no attribute 'items'
Backtrace:
  File "/data/srv/wmagent/v1.1.15.patch4/sw/slc7_amd64_gcc630/cms/wmagent/1.1.15.patch4/lib/python2.7/site-packages/WMCore/WorkerThreads/BaseWorkerThread.py", line 213, in __call__
    raise ex
```

so it fails to fetch the agent info from the auxiliary db.
diff --git a/src/python/WMComponent/AgentStatusWatcher/DrainStatusPoller.py b/src/python/WMComponent/AgentStatusWatcher/DrainStatusPoller.py
index 0e2c0d3be..c4a9e29f5 100644
--- a/src/python/WMComponent/AgentStatusWatcher/DrainStatusPoller.py
+++ b/src/python/WMComponent/AgentStatusWatcher/DrainStatusPoller.py
@@ -41,6 +41,9 @@ class DrainStatusPoller(BaseWorkerThread):
         """
         logging.info("Running agent drain algorithm...")
         self.agentConfig = self.reqAuxDB.getWMAgentConfig(self.config.Agent.hostName)
+        if not self.agentConfig:
+            logging.error("Failed to fetch agent configuration from the auxiliary DB")
+            return
 
         if isDrainMode(self.config):
             # check to see if the agent hit any speed drain thresholds
['src/python/WMComponent/AgentStatusWatcher/DrainStatusPoller.py']