Mongoose : objects not found after synchronous saves

gistfile1.js

var mongoose        = require('mongoose');

var File = new mongoose.Schema({
      servername      : { type: String, index: { unique: true } }
    , originalname    : String
});

var FileModel = mongoose.model('File', File);

function connect(callback) {
    mongoose.connect("mongodb://localhost:27017/test-inserts", function(err) {
        if(err) {
            console.log(err);
            return;
        }
        console.log(err || "Connected to MongoDB");
        callback();
    });
}

function success(doc) {
    console.log("success!", doc);
}

function error(err) {
    console.log("ERROR! ",err.message);
}

connect(function() {
    FileModel.remove({}, function(err) {
        if(err) {
            error(err || new Error('Error emptying collection'));
            return;
        }
        for(var i=0;i<10;i++) {
            var file = new FileModel({servername: "hello"+i, originalname: "world"+i});
            file.save(function(serr) {
                FileModel.findOne({servername: "hello"+i}, function(err, doc) {
                    if(err || !doc) {
                        error(err || new Error('File not found'));
                        return;
                    }
                    success(null, doc);
                });
            });
        }
    });
});