Comment 1 for bug 1086226

yeah, this is a bug. It should be something in the 400s I suspect, as the server is behaving correctly, and it is up to the tenant to remedy the situation.

409 seems like a reasonable solution, though I usually think of it as being used when the tenant is making a request that would put the system in an inconsistent state. Another option would just be to return a generic 400 request.

salvatore (API guru) should probably figure out which is more consistent.