gistfile1.js

var githubhook = require('githubhook');
var github = githubhook({/* options */});

github.listen();

var mergeRegex = /^Merge pull request (#\d)+ from/;
github.on('*', function (event, repo, ref, data) {
        console.log('Hook received for',repo);

        var head = data.head_commit;

        var pusher = data.pusher.name;

        var matches = mergeRegex.exec(head.message);
        if (matches === null) {
                console.log('commit pushed', head.id.substr(0,8));
        } else {
                console.log('Pull request merged', matches[1]);
        }
});