I believe the bug being referred to is "9862 Separate group for ipblock-exempt on en.wikipedia".
AB provided a patch which added an ipblock-exempt group, which a user could be added to to be exempt from IP blocks (but not from username blocks), but this was rejected because the power wouldn't be available to bureaucrats (the software only allowed stewards to perform such a feat). Then Simetrical made a patch to implement Special:MakeIPExempt which would allow bureaucrats to put users in the group, but this patch was rejected because it was considered too messy to use yet another Special: extension. Bug 6711 addressed this, and is now resolved. It adds a Special:Userrights page and exactly who has the power to do what can be configured on a site by site basis. So now that 6711 is resolved it seems to me that AB's patch should now be accepted. Then, any wiki running the new version of the software can allow assignments to the ipblock-exempt group using Special:Userrights, so long as the appropriate $wgAddGroups line is added to the config file.
Once the patch is accepted, it'd be up to the individual projects to decide who, if anyone, should be allowed to assign users to this group. Presumably for wikien it'll be the bureaucrats, who will assign/remove users to the group after a successful !vote. Alternatively, sysops could be trusted to assign/remove users to the group, either after a successful !vote, or under their own judgment.
Individual projects can already decide that. The patch that hasn't been accepted is just one to add the ability to enwiki, that's one project, and it's a project that has not made the decision to add the ability. The MediaWiki code already has all the functionality it needs in this matter, it simply needs to be turned on in the settings for an individual project. If a consensus is found to exist to turn it on for enwiki then the patch will be accepted, but that consensus does not exist (or, at least, hasn't been shown to exist).