def _image_for_job_id(self, job_id):
        if job_id not in self._jobid2image:
            expected_image = db.session.query(
                SnapshotImage.id,
            ).filter(
                SnapshotImage.job_id == job_id,
            ).scalar()
            # note that expected_image could be None
            self._jobid2image[job_id] = expected_image
        return self._jobid2image[job_id]
JRPC test: configuration.sc.channel.getCompatible
dataset/ETHPy150Open dropbox/changes/changes/buildsteps/default.py/DefaultBuildStep._image_for_job_id--crossover with--dataset/ETHPy150Open satnet-project/server/services/scheduling/tests/jrpc/test_compatibility.py/TestCompatibilityViews.test_sc_channel_get_compatible