Function another_instance_running 

pub(crate) fn another_instance_running(
    config_dir: &Path,
    app_support: &Path,
) -> bool

Whether another live forge holds a lock under app_support for a config dir other than config_dir.

The machine-wide app-support tree is shared by every config dir, so a boot that changes something there - the browser host’s per-version prune - has to ask whether a peer is still running first. A lock file whose flock nobody holds is a leftover from a process that exited, not a peer.