Problem:
If you create manually a new release group (not through creating a release) and move a release into it, the release group does not seem to get the earliest release date info from the releases. As a result the release group is not sorted correctly. See how this release group is put to the end of the list under singles on the artist page: http://musicbrainz.org/release-group/29fe2b7e-e25c-4594-baaf-ab49da8d7b52 → http://musicbrainz.org/artist/8b506e4a-c343-467b-aad6-300a9bfac355

Steps to take to recreate:
1. Create a new release group
2. Move an existing release to that group