OnRenderImage with linear color space on android gammafies image

If I add a post effect to the camera like this:
void OnRenderImage(RenderTexture source, RenderTexture destination)
{
Graphics.Blit(source, destination);
}
The result looks as if each pixel was square rooted, i.e. the result is washed out.
I would expect (want) it to do nothing.
This happens with any post effect that I add, but the simplest example is above.
It seems like source or destination has its linear flag set incorrectly or possibly something somewhere else is not taking into account the fact that linear rendering is being used.

Does anyone know of a solution or workaround?
Thanks!

David Wu