I think I've confused myself here (not hard these days!), I have the branch_4x code checked out, and that version definitely supports starting Solr with no cores at all. I still get an Admin UI and I can then use that to create cores/collections starting from a clean slate.
Does that work in 4.4.0 or is it a yet to be released feature? I saw the feature in 4.4.0: * Added a new system wide info admin handler that exposes the system info that could previously only be retrieved using a SolrCore. But that's not the same thing, right? I tried starting a 4.4.0 setup with 0 core.properties files and get the (old) error & red box about no cores are available, so the admin UI doesn't appear at all.
