Did a bandaid patch for bug number 1144. The views were fixed earlier but the new pages in acs-subsite assumed that a user could only belong to one relseg at a time.
Fix for #1144: duplicate rows in cc_users. group::add_member will now delete any memberhip_rel or child thereof before inserting the new relation. It didn't before, and this could cause a user to have both a membership_rel and an admin_rel relation to the registered_users group.