gitlab tree api returns [] instead of 404 for non-existent dir

Summary

The tree API returns [] for a non-existent path instead of 404.

Steps to reproduce

curl https://gitlab.com/api/v3/projects/13083/repository/tree?path=bogus

Example Project

(that's gitlab-ce linked above)

What is the current bug behavior?

I get 200 OK, content []

What is the expected correct behavior?

I should get a 404.

Availability and Testing

Add request spec to ensure 404 is returned.