Comment 1 for bug 1573630

The tricky bit here is verifying between a valid key value pair and a key value pair that simply has no failures. The subunit2sql DB in both cases returns an empty list so by itself you can't differentiate. We want to make sure we return a 4xx response on the invalid case. I'm thinking the way forward here is to simply add an additional key, value lookup call when there is an empty list. If the key is valid return an empty feed, else return 4xx.