Closed Heavy Pipes don't block light effectively

409 here with another aesthetic/graphical issue.

I noticed that when building things, an area that was supposed to be completely dark was lit up during the day:



Here's a comparison shot at night.



Upon further investigation, I noticed that the Heavy Pipe I was using in the background is letting small amounts of light pass through it for some unknown reason as if it were, say, glass or another material with transparent bits.


This makes absolutely no sense whatsoever due to Heavy Pipe lacking transparent parts like Glass or Metal Bars, so I assume that it is a bug or oversight.

 

I've noticed that, too.

 

Confirmed. The material "heavypipe" has transparent render parameters.