OL 2.13rc2 layer.setVisibility() with TileManager does not always work with GeoExt 1.x

When the TileManager is enabled, toggling between two different layers via layer.setVisibility(true|false) will sometimes result in no tiles being loaded. 

This is always the case when loading a portion of a layer which has not previously been loaded. Panning very slightly or zooming in/out will always force the tiles to then be loaded.

jsfiddle example: http://jsfiddle.net/HN5CQ/4/