[124.0] Can build switch at tunnel portal

[ceeac]

If there is a raised terrain to the left or right of a tunnel portal, it is possible to build a switch on the tunnel portal tile by building a tunnel from the portal into the raised terrain tile.

[danivenk]

I believe this has been in the game for quite some time now. The question becomes of course if this is desirable behavior. Same could be said for the fact that you can create a curve/diagonal through the tunnel portal itself.
What would be your reasoning behind it being or not being a bug ceeac?
Cause I believe this is one of those unexpected behaviors that AFAIK depending on who you talk to people either say it is exploiting bugs or are just using all features that are in the game (unintended or not).

Please share your reasoning and arguments.

[prissi]

I think and tile on the ground and with ground slope!=way slope should not allow for curves. These include bridge ramps too ... investigating.

[prissi]

I consider this a fringe case as the clearance it ok and thus a know bug and feature.