GL1's R_CreateImage sets GL texture to 0 before it ends, so border color is not
applied to the fog image. GL_CLAMP is not used for fog image (in either renderer),
so it would presumably not be used even if applied to the fog image.
If you tried to draw the last loaded image, gl texture 0 (which is appearently white)
was used because renderer thought the image was already bound.
Why OpenGL1 renderer binds texture 0, I have no idea. It's been removed from OpenGL2.