That was on purpose. 

I didn't know whether I would have finished & ran https://bugzilla.mozilla.org/show_bug.cgi?id=880188 when this goes in production. As long as that bug isn't done, existing apps will have empty `_developer_name` in the db. I wanted to avoid forcing a re-review on those apps if I could, so if the old developer_name, whatever its provenance is, matches the new one, we skip the re-review. 

(per comments in bug 880188 we don't want to force re-review on all our existing apps when we deploy this)