Also delete the job key when expiring a job

Otherwise, we can't requeue the job

buildman/manager/ephemeral.py

@@ -170,6 +170,13 @@ class EphemeralBuilderManager(BaseManager):
     got_lock = yield From(self._take_etcd_atomic_lock('job-expired', build_job.build_uuid,
                                                       execution_id))
     if got_lock:
+      try:
+        # Clean up the bookkeeping for the job.
+        yield From(self._etcd_client.delete(self._etcd_job_key(build_job)))
+      except (KeyError, etcd.EtcdKeyError):
+        logger.debug('Could not delete job key %s; might have been removed already',
+                     build_job.build_uuid)
+
       logger.error('[BUILD INTERNAL ERROR] Build ID: %s. Exec name: %s. Exec ID: %s',
                     build_job.build_uuid, executor_name, execution_id)
       yield From(self.job_complete_callback(build_job, BuildJobResult.INCOMPLETE, executor_name,