Fix online plan bug with multiple serial summers and certain no-ops

The comments summarize this one. But the take away is:

1) We need to look at even more robust tests, and try to think about what a correctness proof for the plans would look like.

2) There are still many opportunities to make storm plans with fewer bolts. We should take a look at that as we look to squeeze all the perf we can out of storm.
i don't think we could do that right? the map side aggregation would be broken then?