asyncio.CancelledError没被抓住

为什么 CancelledError 在这个例子中没有被抓住?

import asyncio

q = asyncio.Queue()

async def getter():
    try:
        v = await q.get()
        print(f"getter got {v}")
    except asyncio.CancelledError:
        print("getter cancelled")

async def test():
    task = asyncio.ensure_future(getter())
    task.cancel()
    await task

def main():
    loop = asyncio.get_event_loop()
    loop.run_until_complete(test())

if __name__ == '__main__':
    main()

我希望得到“getter cancelled”消息,但收到了堆栈跟踪:

Traceback (most recent call last):
  File "ce.py", line 22, in 
    main()
  File "ce.py", line 19, in main
    loop.run_until_complete(test())
  File "/usr/lib64/python3.6/asyncio/base_events.py", line 468, in run_until_complete
    return future.result()
concurrent.futures._base.CancelledError

Task.cancel 国家:

这将安排一个CancelledError被扔进 有机会清理甚至拒绝使用 尝试/排除/最后。