dom0 uses fedora 23 as of now. Both /etc/fedora-release and
/etc/redhat-release are customized for Qubes, because dom0 cannot be
updated so lightheartedly.
The qubes packages for dom0 are only for fedora 20 (older releases) or
fedora 23 (R3.2). Because of the Qubes security model there is no
immediate reason to have a cutting-edge dom0. The problems may be with
hardware support...
--
Alex