Set changed size during iteration

[xian18]

描述你遇到的问题:

收到群消息后会出现这个Exception

raceback (most recent call last):
  File "/anaconda3/lib/python3.7/site-packages/graia/broadcast/__init__.py", line 240, in Executor
    await dii.lookup_param(name, annotation, default)
  File "/anaconda3/lib/python3.7/site-packages/graia/broadcast/interfaces/dispatcher.py", line 227, in lookup_param
    lambda x: [DispatcherSource(self.execution_contexts[-1].always_dispatchers)]
  File "/anaconda3/lib/python3.7/site-packages/graia/broadcast/interfaces/dispatcher.py", line 143, in dispatcher_generator
    for dispatcher in source.dispatchers:
RuntimeError: Set changed size during iteration

复现步骤:
该 BUG 会在进行以下操作后出现:

1. 发送两条群消息

发生错误的代码

from graia.application.entry import GraiaMiraiApplication
from graia.broadcast import Broadcast
import asyncio
from graia.application.session import Session

loop=asyncio.get_event_loop()
bcc=Broadcast(loop=loop)
app=GraiaMiraiApplication(
    broadcast=bcc,
    connect_info=Session(
        host='http://127.0.0.1:800000',   #你mirai-api-http监听的地址以及端口
        authKey='mirai-api-http-token',      #在mirai-api-http设置的authKey
        account="qq number",             #要使用的对应的bot 的qq号
        websocket=True                  #记得在mirai-api-http里面设置开启websocket
    ),
    enable_chat_log=True,
    debug=True
)
app.launch_blocking()

控制台日志输出截图:

运行环境:

• 操作系统: Ubuntu 18.04
• mirai-core 版本: mirai-console-1.0-M4.jar
• mirai-api-http 版本: mirai-api-http-v1.8.3
• graia-application-mirai 版本: 0.11.0
• 是否出现在机器人长期运行后: 否

额外信息:

只使用BroadCast（在尝试简化代码）貌似没有这个问题.

[GreyElaina]

将 graia-broadcast 更新到 0.5.2 即可.

[GreyElaina]

*0.5.3, 我忘记删abc class的def了(