Function spawn_with_environment 

pub fn spawn_with_environment(
    command: &mut Command,
    stdio: SpawnStdio<'_>,
    environment: SyncEnvironment,
    shutdown_timeout: Option<fn() -> Duration>,
) -> Result<SpawnedChild>

Spawn a contained child using an explicit live environment base.

The selected synchronous substrate owns the contained-child drop policy; the optional historical shutdown callback is accepted for source compatibility but is not evaluated by this boundary.