changelog.php

<?php
$token = '<yourtoken>';

// Find latest version
exec('git tag', $tags, $return);
usort($tags, 'version_compare');
$latest = array_pop($tags);

// Get commits since latest version
exec('git log ' . $latest . '...HEAD --oneline', $commits, $return);

// Filter commits that reference an issue
$issues = array();

foreach ($commits as $commit) {
    if (preg_match('/[close|closes|fix|fixes] #([0-9]+)/i', $commit, $matches) && isset($matches[1])) {
        $issues[] = $matches[1];
    }
}

sort($issues);

// Query GitHub
$url     = 'https://api.github.com/repos/sebastianbergmann/phpunit/issues/';
$headers = array(
    'Authorization: token ' . $token,
    'User-Agent: php-curl'
);

foreach ($issues as $id) {
    $ch = curl_init($url . $id);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

    $issue = json_decode(curl_exec($ch), true);

    print $id . ": " . $issue['title'] . " (" . $issue['url'] . ")\n";
}