Yes, that was the missing data - thank you. I still don't see the need for smartmatch. Instead, here is an SSCCE using a standard m match with a negative look-ahead:

use strict;
use warnings;

use Test::More;

my @good = (
        'redhat-release',
        'redhat-release-server'
);

my @bad = (
        'redhat-release-notes',
        'any-old-nonsense'
);

my $re = qr/^redhat-release(?!-notes)/;

plan tests => @good + @bad;

for my $str (@good) {
        like ($str, $re, "$str matched");
}
for my $str (@bad) {
        unlike ($str, $re, "$str not matched");
}
[download]

See How to ask better questions using Test::More and sample data for thoughts about presenting questions in this form.