Comment 9 for bug 1857306

The check for osapi_compute_unique_server_name_scope is likely going to have to move from the per-cell DB API code to the REST API service layer and if set will iterate the cells looking for a duplicate and return the 409 response if a duplicate is found. That could be racy though so conductor will likely still need to handle the InstanceExists error, but I'm not sure what to do with it. I guess one option is just not creating the instance in the cell0/non-cell0 DB and also deleting the build_requests record for that instance, but that means having a response with a server id to not having one, which might be a bit weird for the user experience. Alternatively the DB API instance_create method is going to have to handle creating a server with a duplicate name but putting it into ERROR status immediately.