pub fn fail_progress(home: &Path, detail: &str) -> Result<bool>Expand description
Record detail as the failure of the upgrade request that is asking,
unless a handover is already in flight (parking / restarting): that
handover is not this request’s to fail. The check and the write happen
under the same lock as write_progress, so a handover that records
parking in between cannot be overwritten. Returns whether it was written.