prestart.sh: fix check for fedora/redhat/centos

In fixup_udev(), we need to detect rhel or centos.

Both RHEL, CentOS and Fedora have /etc/redhat-release, in addition
Fedora has /etc/fedora-release and CentOS 6 has /etc/centos-release
(while Centos 4 and 5 don't).

So we have to check that
- fedora-release is NOT present
and
- redhat-release is present

We do it in two steps.

Signed-off-by: Kir Kolyshkin <kir@openvz.org>
1 file changed