Fix a few issues with some recent changes to suite_scheduler.

EnumeratorException was not fully referenced causing crashes.
In deduping_scheduler a function definition was missing self.

Start printing tracebacks in the error messages logged in emailed to make it
easier to track down issues like the above.

TEST=Unittests
BUG=None

Change-Id: Ieee88f9a18debedb1dafdd92fd811d271e4f3816
Reviewed-on: https://gerrit.chromium.org/gerrit/26943
Reviewed-by: Chris Masone <cmasone@chromium.org>
Commit-Ready: Scott Zawalski <scottz@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Tested-by: Scott Zawalski <scottz@chromium.org>
diff --git a/site_utils/suite_scheduler/driver.py b/site_utils/suite_scheduler/driver.py
index d5fdba5..dd6d483 100644
--- a/site_utils/suite_scheduler/driver.py
+++ b/site_utils/suite_scheduler/driver.py
@@ -112,7 +112,7 @@
         while True:
             try:
                 self.HandleEventsOnce(mv)
-            except EnumeratorException as e:
+            except board_enumerator.EnumeratorException as e:
                 logging.warn('Failed to enumerate boards: %r', e)
             mv.Update()
             time.sleep(self._LOOP_INTERVAL_SECONDS)