Context

Any AsyncMongoClient created after the first on a given asyncio event loop will experience a server selection timeout on its first operation. With the default timeout configuration, this will cause a 20-second delay for this first operation, for each client after the first.

A brief example:

for i in range(2): 
    start = time.monotonic() client = AsyncMongoClient()     
    await client.admin.command("ping") 
    await client.close() 
    print(f"Client {i} took {time.monotonic() - start} seconds")  

This will output the following:

Client 0 took 0.004705582978203893 seconds
Client 1 took 20.0034456250141374767 seconds

This timeout is caused by the `_async_receive` coroutine waited on by `async_receive_data` not properly cancelling when its parent task is cancelled. Explicitly cancelling this task when an `asyncio.CancelledError` is raised solves the problem.

Definition of done

AsyncMongoClient instances after the first on a given asyncio event loop should not experience a server selection timeout before their first operation succeeds.