buildbot: improve error handling

buildbot.py

@@ -482,19 +482,13 @@ if __name__ == '__main__':
     __main() # start the Listener thread
     logger.info('Listener started.')
     while True:
+        try:
             try:
                 ret = 1
                 ret = jobsmgr.tick()
             except Exception:
-            try:
                 jobsmgr.clean_failed_job()
-            except Exception:
                 print_exc_plus()
-            print_exc_plus()
-        except KeyboardInterrupt:
-            logger.info('KeyboardInterrupt')
-            print_exc_plus()
-            break
             if ret is None:
                 sleep(1)
             elif ret == 0:
@@ -503,3 +497,9 @@ if __name__ == '__main__':
                 sleep(ret)
             else:
                 sleep(1)
+        except Exception:
+            print_exc_plus()
+        except KeyboardInterrupt:
+            logger.info('KeyboardInterrupt')
+            print_exc_plus()
+            break