NodeBB patch - Remove OP and replace it with first reply

debug.js

// paste this in https://github.com/NodeBB/NodeBB/blob/master/src/routes/debug.js
// and then don't forget to remove it!

router.get('/remove-op', function(req, res) {
	var db = require('../database'),
		async = require('async');

	db.getSortedSetRange('topics:tid', 0, -1, function(err, tids) {
		async.eachLimit(tids, 50, function(tid, next) {
			db.getSortedSetRange('tid:' + tid + ':posts', 0, 0, function(err, pid) {
				if (err) {
					throw new Error(err);
				}

				pid = pid[0];

				db.sortedSetRemove('tid:' + tid + ':posts', pid, function(err) {
					if (err) {
						throw new Error(err);
					}

					db.setObjectField('topic:' + tid, 'mainPid', pid, next);
				});
			});
		}, function(err) {
			if (err) {
				throw new Error(err);
			}

			res.json({status: true});
		});
	});
});