Updating a Topology's name to a conflicting value returns incorrect error

[ocket8888]

This Bug Report affects these Traffic Control components:

• Traffic Ops

What did you do?

$ topost -k topologies '{"name": "dev", "nodes": [{"cachegroup": "dev"}]}' > /dev/null
$ topost -k topologies '{"name": "dev-1", "nodes": [{"cachegroup": "dev"}]}' > /dev/null
$ toput -kp 'topologies?name=dev' '{"name": "dev-1", "nodes": [{"cachegroup": "dev"}]}'

What did you expect to happen?

400 Bad Request response:

{
	"alerts": [
		{
			"text": "topology name 'dev-1' already exists.",
			"level": "error"
		}
	]
}

(note that this is done appropriately on creation/POST requests).

What actually happened?

500 Internal Server Error response:

{
	"alerts": [
		{
			"text": "Internal Server Error",
			"level": "error"
		}
	]
}