Submitting an erroneous build request will create a QUEUED build and log nothing

Example:

We submitted a malformed build request with the field "job-name" instead of "job_name". The API returns a 500 with response: `{"error": "__init__() got an unexpected keyword argument 'job-name'"}`.

That error message is not that bad (although it could be improved), but the bigger problem is that a new build with the provided parameters now shows up in the queue API response (and will stay there for the lifetime of the master process).

Also, there is no sign of this "queued" build in the master logs at all -- no sign of the error returned to the client, and no mention of any build with that id.

Note that the build that shows up in the queue api is not actually queued, it's just a harmless leftover of the bad request -- although it is pretty confusing if you don't know what's going on.