Painting again after saving a HLMS is not possible

[spookyboo]

Load a Pbs material, paint on the diffuse texture, save the material (updated texture is also saved). Then create a new paintlayer. Paint again on the texture layer. Painting is still done (see textures in the /temp directory). The TextureLayer::blitTexture however doesn't seem to work anymore (is it still the same datablock?).