Function update_job_for_agent 

pub fn update_job_for_agent(
    config: &Config,
    job_id: &str,
    agent_alias: &str,
    patch: CronJobPatch,
) -> Result<CronJob, Error>

Patch a job only if agent_alias owns it, with the ownership test carried into the UPDATE itself rather than performed as a separate read. See remove_job_for_agent for why the separate read is not enough.