Fix miscellaneous prod bugs.

impl/prod/datastore_key.go

Index: impl/prod/datastore_key.go
diff --git a/impl/prod/datastore_key.go b/impl/prod/datastore_key.go
index fde1c970f405b0dbb3e5eba12576089aceb55c5a..23d8fe814c84fb4b6273dc869b33dc406325f9c1 100644
--- a/impl/prod/datastore_key.go
+++ b/impl/prod/datastore_key.go
@@ -19,11 +19,17 @@ func (k dsKeyImpl) Parent() ds.Key { return dsR2F(k.Key.Parent()) }
 
 // dsR2F (DS real-to-fake) converts an SDK Key to a ds.Key
 func dsR2F(k *datastore.Key) ds.Key {
+	if k == nil {
+		return nil
+	}
 	return dsKeyImpl{k}
 }
 
 // dsF2R (DS fake-to-real) converts a DSKey back to an SDK *Key.
 func dsF2R(k ds.Key) *datastore.Key {
+	if k == nil {
+		return nil
+	}
 	if rkey, ok := k.(dsKeyImpl); ok {
 		return rkey.Key
 	}