Between is_fedora, is_ubuntu and is_suse, we can make the code a bit
simpler to read. We also use exit_distro_not_supported to identify
places where we need implementation details for new distros.
As "/sbin/service --skip-redirect" is Fedora-specific, guard this with a
is_fedora test too.
Change-Id: Ic77c0697ed9be0dbb5df8e73da93463e76025f0c
00011c0847