[autotest] Set shard to NULL for completed jobs.

Completed job's shards are set to NULL to signal they should be
uploaded to the master again.

BUG=None
DEPLOY=scheduler
TEST=Run suites

Change-Id: Icd040c895ca6f2a5e3cfcc53e762a94f5b442f58
Reviewed-on: https://chromium-review.googlesource.com/218721
Reviewed-by: Prashanth B <beeps@chromium.org>
Commit-Queue: Jakob Jülich <jakobjuelich@chromium.org>
Tested-by: Jakob Jülich <jakobjuelich@chromium.org>
diff --git a/scheduler/scheduler_models_unittest.py b/scheduler/scheduler_models_unittest.py
index 1421f72..010b44a 100755
--- a/scheduler/scheduler_models_unittest.py
+++ b/scheduler/scheduler_models_unittest.py
@@ -299,12 +299,15 @@
         for status in host_queue_entry_states.Status.values:
             hqe = self._create_hqe(hosts=[1])
             hqe.started_on = datetime.datetime.now()
+            hqe.job.update_field('shard_id', 3)
             self.assertIsNone(hqe.finished_on)
             hqe.set_status(status)
             if status in host_queue_entry_states.COMPLETE_STATUSES:
                 self.assertIsNotNone(hqe.finished_on)
+                self.assertIsNone(hqe.job.shard_id)
             else:
                 self.assertIsNone(hqe.finished_on)
+                self.assertEquals(hqe.job.shard_id, 3)
 
 
 class JobTest(BaseSchedulerModelsTest):