autotest: log uncaught exception in monitor_db

BUG=chromium:718615
TEST=None

Change-Id: Ifbd87c700c17cf8d6dbeb1ccbe5c61f1b134933a
Reviewed-on: https://chromium-review.googlesource.com/497828
Commit-Ready: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Michael Tang <ntang@chromium.org>
diff --git a/scheduler/monitor_db.py b/scheduler/monitor_db.py
index 114e959..0aee2f6 100755
--- a/scheduler/monitor_db.py
+++ b/scheduler/monitor_db.py
@@ -190,6 +190,7 @@
           # for scheduler role. Thus do not send email for it.
           logging.exception(e)
       except Exception:
+          logging.exception('Uncaught exception, terminating monitor_db.')
           metrics.Counter('chromeos/autotest/scheduler/uncaught_exception'
                           ).increment()