I've been experiencing a bug while trying to write a buffer to a file using Gio.File's replace_contents_async. It's been writing strange characters to the output.

Here's a code snippet showing this unexpected behavior:

const Gio = imports.gi.Gio;
const Lang = imports.lang;
const Mainloop = imports.mainloop;

let buffer = "lala";
let file = Gio.file_new_for_path("output.json");
file.replace_contents_async(buffer, null, false, Gio.FileCreateFlags.REPLACE_DESTINATION, null, 
    Lang.bind(this, function() {
        log("bye!");
    }));

Mainloop.run();

It's the same when using ByteArray:

const ByteArray = imports.byteArray;
const Gio = imports.gi.Gio;
const Lang = imports.lang;
const Mainloop = imports.mainloop;

let byteArray = ByteArray.fromString('lala');;
let file = Gio.file_new_for_path("output.json");
file.replace_contents_async(byteArray, null, false, Gio.FileCreateFlags.REPLACE_DESTINATION, null, 
    Lang.bind(this, function() {
        log("bye!");
    }));

Mainloop.run();

* Gio.file.replace_contents() works fine.