title: onBitmapLoaded of Target object not called on first load
body: <p>In my function :</p>
  
  <pre><code>public void getPointMarkerFromUrl(final String url, final OnBitmapDescriptorRetrievedListener listener) {
  final int maxSize = context.getResources().getDimensionPixelSize(R.dimen.icon_max_size);
  Target t = new Target() {
    @Override
    public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
      if (bitmap != null)
        listener.bitmapRetrieved(getBitmapDescriptorInCache(url, bitmap));
      else
        loadDefaultMarker(listener);
    }
  
    @Override
    public void onBitmapFailed(Drawable errorDrawable) {
      loadDefaultMarker(listener);
    }
  
    @Override
    public void onPrepareLoad(Drawable placeHolderDrawable) {
    }
  };
  
  Picasso.with(context)
      .load(url)
      .resize(maxSize, maxSize)
      .into(t);
  }
  </code></pre>
  
  <p>The onBitmapLoaded() is never called the first time I load pictures. I've read some topic like <a href="https://github.com/square/picasso/issues/39">https://github.com/square/picasso/issues/39</a> which recommand to use fetch(Target t) method (it seems to be a problem of weak reference...), but this function is not  available in the last release of picasso (2.3.2). I've only a fetch() method, but I cannot use into(mytarget) at the same time</p>
  
  <p>Could you explain me how to use fetch() with a custom Target please ? Thank you.</p>
  
  <p>Doc : <a href="http://square.github.io/picasso/javadoc/com/squareup/picasso/RequestCreator.html#fetch--">http://square.github.io/picasso/javadoc/com/squareup/picasso/RequestCreator.html#fetch--</a></p>