def _find_job(self, master_base_url, job_name, changes_bid):
        # Check the queue first to ensure that we don't miss a transition
        # from queue -> active jobs
        item_id = self._find_queue_item_id(master_base_url, changes_bid)
        build_no = None
        if item_id:
            # Saw it in the queue, so we don't know the build number yet.
            build_no = None
        else:
            # Didn't see it in the queue, look for the build number on the assumption that it has begun.
            build_no = self._find_build_no(master_base_url, job_name, changes_bid)

        if build_no or item_id:
            # If we found either, we know the Jenkins build exists and we can probably find it again.
            return {
                'job_name': job_name,
                'queued': bool(item_id),
                'item_id': item_id,
                'build_no': build_no,
                'uri': None,
            }
        return None
Given a job identifier, we attempt to poll the various endpoints
dataset/ETHPy150Open dropbox/changes/changes/backends/jenkins/builder.py/JenkinsBuilder._find_job