CB-352 changed the API to accept published_on instead of created as a sort method. While this probably has a point, nothing was done to ensure backwards compatibility. This broke MusicBrainz's usage of the API (MBS-11077) and might have affected other API consumers. On critiquebrainz/ws/review/views.py created should be accepted, but mapped to published_on (in the same way rating is mapped to popularity), in case someone else still is using sort=created and getting back errors like MusicBrainz was.

While at it, the docs should be updated (last I checked they still showed created as the correct parameter)