tracing logs are printed twice

[Bergmann89]

Hey guys,

I discovered a strange issue with the tracing feature enabled: My tracing logs are displayed twice. I have set up tracing with the following code:

World::cucumber()
     .configure_and_init_tracing(DefaultFields::new(), Format::default(), move |layer| {
            registry().with(EnvFilter::from_default_env().and_then(layer))
        }
    });

And then I have some log outputs inside my step, like this:

#[when(regex = r"^I establish a (?:\s+([^\s]+))? session(?: to ([^\s]+))?$")]
async fn connect(
    world: &mut World,
    mode: Optional<String>,
    remote: Optional<String>,
) -> Result<(), Error> {
    tracing::trace!("connect (mode={mode:?}, remote={remote:?})");

    // [...]

    let span = debug_span!(parent: None, "Session");
    let _span = span.enter();

    let session = open(config).await?;
    world.session = Some(session);
}

I see the log output twice:

2025-03-03T13:44:55.853009Z TRACE scenario:step: swarm_tests::steps: connect (mode=Optional(None), remote=Optional(Some("router-1")))
2025-03-03T13:44:55.853050Z DEBUG scenario:step: swarm_tests::steps: Get address for container `router-1`
2025-03-03T13:44:55.854279Z DEBUG scenario:step: swarm_tests::steps: Address for container `router-1` is `172.19.0.3`
[...]
2025-03-03T13:44:55.853009Z TRACE scenario:step: swarm_tests::steps: connect (mode=Optional(None), remote=Optional(Some("router-1")))
2025-03-03T13:44:55.853050Z DEBUG scenario:step: swarm_tests::steps: Get address for container `router-1`
2025-03-03T13:44:55.854279Z DEBUG scenario:step: swarm_tests::steps: Address for container `router-1` is `172.19.0.3`
[...]

The lines are completely identical. The strange thing is, that this happens for the steps after I created a new root span. I had to create the span as workaround, because cucumber will wait until the current span is closed, which will never happen if my session is stored in my world.