"Show-rail-blocks" debug option assigned colors not ideal

[Artentus]

So the new debug option to show rail blocks is nice for creating complex rail intersections.
However, sometimes two directly adjacent blocks will get the same color and appear as one block, which kind of defies the purpos of the feature. Imo blocks should always be colored in a way that adjacent blocks have different colors.

There are no real steps to reproduce because I guess the colors are just chosen at random. Just build a decently complex intersection and it is likely to happen.