Sorry, seems I was working on old intel. 5.9 is now slated to be a full release again.
About the development versioning... Many projects currently prefer (as do I for some time now) the -0.1 version for development, since it makes for easier sorting of isos or packages in a directory listing, as opposed to something like 6.0beta, which will be sorted as a higher version than plain 6.0. I've seen it happen in vasm, for example.