botserver: Make handle_bot logic more concise.

zulip_botserver/zulip_botserver/server.py

@@ -104,15 +104,14 @@ bots_config = {}  # type: Dict[str, Dict[str, str]]
 @app.route('/', methods=['POST'])
 def handle_bot() -> Union[str, BadRequest]:
     event = request.get_json(force=True)
-    bot = None
     for bot_name, config in bots_config.items():
         if config['email'] == event['bot_email']:
             bot = bot_name
-    if bot is None:
+            break
+    else:
         return BadRequest("Cannot find a bot with email {} in the bot server "
                           "configuration file. Do the emails in your flaskbotrc "
                           "match the bot emails on the server?".format(event['bot_email']))
-    else:
     lib_module = app.config.get("BOTS_LIB_MODULES", {})[bot]
     bot_handler = app.config.get("BOT_HANDLERS", {})[bot]
     message_handler = app.config.get("MESSAGE_HANDLERS", {})[bot]