creating a new user group requires reindex

somewhere it should be noted that creating a new user group in order to find issues (Find Issues -> Assignee: Specific Group) requires reindexing before the search will work.

probably this doesn't work in the expected way: currently, the groups are stored in the issue index and issues are returned based on whether the group name is found in the index. this means that if I add a user to a group, all the issues need to be reindexed. it seems like it would be better to pull a list of all the users in the group at search time, and find issues associated with any of these users.