We have a couple of instances of GeoServer running, one of which is the latest version and the other is version 2.1.3.
The older version has Ordnance Survey base mapping which is loaded as a number of EPSG:27700 image-mosaics. These are then reprojected by GeoServer into the Google projection EPSG:900913 and displayed as part of a layer group where the style switches the layers on / off depending on the scale. We believe this is a fairly standard use of GeoServer to provide a base map coverage and it works fine.
In the newest versions of GeoServer the same base map layer creates a horrible orange coloured map as it seems to be breaking the colour banding of the layers. Seems to be turning the large swaths of blue sea into orange, as well as screwing the colours on the rest of the map. I can't upload a screenshot as our organisations internet policies restrict it.
Please note, you need to reproject two image-mosaics and combine them in a layer group or GetMap to reproduce the error.
We wondered if anyone else has experienced the bug in the latest versions, and whether there are any solutions or workarounds anyone has come across.