LogDog: Handle archive failures.

appengine/logdog/coordinator/backend/archiveCron.go

Index: appengine/logdog/coordinator/backend/archiveCron.go
diff --git a/appengine/logdog/coordinator/backend/archiveCron.go b/appengine/logdog/coordinator/backend/archiveCron.go
index f3b5d79e063b6fa2a1c0435ada4a5c63b51968fd..a7e7f32238bd956239a5636e60b9940280d59e2d 100644
--- a/appengine/logdog/coordinator/backend/archiveCron.go
+++ b/appengine/logdog/coordinator/backend/archiveCron.go
@@ -118,6 +118,10 @@ func (b *Backend) archiveCron(c context.Context, complete bool) error {
 	now := clock.Now(c).UTC()
 	q := ds.NewQuery("LogStream")
 
+	// TODO(dnj): Next schema migration, remove this State constraint in favor
+	// of equality filters on _Terminated and ArchiveState.
+	// It is necessary for now since otherwise, *all* archived streams will match
+	// this query!
 	var threshold time.Duration
 	if complete {
 		threshold = cfg.GetCoordinator().ArchiveDelay.Duration()