Async fixture teardown

Hi! I have question regarding how asynchronous fixture teardown (e.g. closing a connection that was open asynchronously) is supposed to work.

When I have a fixture such as:

@pytest.fixture(scope='session')
@async_generator
async def fixture():
    # ... async opening of a connection
    connection = await asyncpg.connect(...)
    await yield_(connection)
    await connection.close()

I am getting the following error: ValueError: Async generator fixture didn't stop.Yield only once.