Fix timeout debug print in tests

Commit 4c6a7744 introduced an error in formatting the queue status.
This corrects that and also changes the print statements to debug
logs so they are easier to follow.

Change-Id: I412ad6c2e460c5ee15cc0e5a3956a513b7cd7138
diff --git a/tests/base.py b/tests/base.py
index e7da178..66bf16a 100755
--- a/tests/base.py
+++ b/tests/base.py
@@ -1296,8 +1296,11 @@
         start = time.time()
         while True:
             if time.time() - start > 10:
-                print('queue status:', ''.join(self.eventQueuesEmpty()))
-                print(self.areAllBuildsWaiting())
+                self.log.debug("Queue status:")
+                for queue in self.event_queues:
+                    self.log.debug("  %s: %s" % (queue, queue.empty()))
+                self.log.debug("All builds waiting: %s" %
+                               (self.areAllBuildsWaiting(),))
                 raise Exception("Timeout waiting for Zuul to settle")
             # Make sure no new events show up while we're checking
             self.worker.lock.acquire()