Well, I'm addressing current blacklisting issues with the AUR [1]. I noticed that some of the packages in the official repos have AUR packages as provides, some of them (well, at least one of them, didn't search for more) were even added due to FRs [2]. Donnu if this applies to [core] and [extra] as well.
Is that regular practice? Imho, we shouldn't do that. The AUR is something to be considered separately. If we start to care about provides/conflicts with AUR packages, we'll need to add all "-devel"/"-svn"/"-git"/"-beta" packages in the AUR to the official packages conflicts and provides as well. And we'll need to start searching for alternative repos to ensure there's no conflict with our official packages. Seriously, we should be consistent here. [1] http://mailman.archlinux.org/pipermail/aur-general/2011-February/013811.html [2] https://bugs.archlinux.org/task/16495