Now that I'm understanding more and more the distinction between lookup and browse webservices, I come to an alternate additional way of obtaining result as in MBS-6114.
Add collection=mbid to /ws/2/release browse request.
http://musicbrainz.org/ws/2/release?collection=f0574792-6af6-481e-8b2f-d5ea9fc59c4d is currently down as currently linked entities for release ws are following :
/ws/2/release artist, label, recording, release-group
(ws ws2 webservice)