gremlin: fix aggregates without time context
gremlin: fix aggregates without time context

lebauce/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,skydive-project/skydive,skydive-project/skydive,lebauce/skydive