overrides/Gio: Guard against repeated _promisify() calls
Calling _promisify() on a method that is already promisified will break it. Fix this with a simple check at the start of the function, and bail out if the method has been promisifed before.
Calling _promisify() on a method that is already promisified will break it. Fix this with a simple check at the start of the function, and bail out if the method has been promisifed before.