Signs do not honor Custom Texturepacks

It appears that the new signs (Oak etc) are hard coded to use the default textures and do not honour custom texturepack textures. This cannot be overridden by modifying the model json to point to other textures either. This breaks coherence of the texturepack.

This did not occur in 1.13 albeit there was only once sign then.

 

Spash screen Mojang.png also seems hardcoded as it will not use the one in assets/minecraft/gui if modified.